| thioesterases and the premature termination of polyketide chain elongation in rifamycin b biosynthesis by amycolatopsis mediterranei s699. | the role of two thioesterase genes in the premature release of polyketide synthase intermediates during rifamycin biosynthesis in the amycolatopsis mediterranei s699 strain was investigated. creation of an in-frame deletion in the rifr gene led to a 30 approximately 60% decrease in the production of both rifamycin b by the s699 strain or a series of tetra- to decaketide shunt products of polyketide chain assembly by the riff strain. since a similar percentage decrease was seen in both genetic ba ... | 2000 | 10908112 |
| effect of uracil on rifamycin sv production by amycolatopsis mediterranei mv35r. | the effect of different organic nitrogen compounds on the production of rifamycin sv by amycolatopsis mediterranei mv35r and their optimum concentrations have been described. results obtained indicate that rifamycin sv production increased from 4020 mg l-1 to 4575 mg l-1 when organic nitrogen compound uracil was added at 0.2% (w/v) concentration to the fermentation medium by a. mediterranei mv35r. the rifamycin sv yield was enhanced by 505 mg l-1 using uracil (2 g l-1) when compared with barbita ... | 2000 | 10886619 |
| expression in escherichia coli, purification and kinetic analysis of the aspartokinase and aspartate semialdehyde dehydrogenase from the rifamycin sv-producing amycolatopsis mediterranei u32. | the operon encoding aspartokinase and aspartate semialdehyde dehydrogenase was cloned and sequenced from rifamycin-sv-producing amycolatopsis mediterranei u32 previously. in the present work, these two genes were introduced into the auxotrophic escherichia coli strain cgsc5074 (ask-) and e. coli x6118 (asd-), respectively. the a. mediterranei u32 asparto-kinase and aspartate semialdehyde dehydrogenase genes can be functionally expressed in e. coli and the gene products are able to substitute for ... | 2000 | 10952005 |
| the importance of homologous recombination in the generation of large deletions in hybrid plasmids in amycolatopsis mediterranei. | the cloning vector prl60 was developed previously as a tool for genetic manipulations in amycolatopsis mediterranei, which produces the commercially and medicinally important antibiotic rifamycin. here, a method based on intraplasmid recombinations is described for the construction of smaller plasmids in a. mediterranei, which also helped in delimiting the origin of replication (pa-rep) of the parent plasmid. the strategy involved the cloning of a selectable marker, erythromycin resistance gene ... | 2000 | 10610815 |
| biosynthesis of l-p-hydroxyphenylglycine, a non-proteinogenic amino acid constituent of peptide antibiotics. | the non-proteinogenic amino acid p-hydroxyphenylglycine is a crucial component of certain peptidic natural products synthesized by a non-ribosomal peptide synthetase mechanism. in particular, for the vancomycin group of antibiotics p-hydroxyphenylglycine plays a structural role in formation of the rigid conformation of the central heptapeptide aglycone in addition to being the site of glycosylation. initial labeling studies suggested tyrosine was a precursor of p-hydroxyphenylglycine but the spe ... | 2000 | 11137816 |
| three new species of the genus actinobispora of the family pseudonocardiaceae, actinobispora alaniniphila sp. nov., actinobispora aurantiaca sp. nov. and actinobispora xinjiangensis sp. nov. | the genus actinobispora jiang et al. is characterized by the formation of longitudinally paired spores on both the vegetative and the aerial mycelium, absence of mycolic acid, cell wall chemotype iv (containing meso-diaminopimelic acid as the diamino acid, galactose and arabinose), pvi and mk-9(h2). comparative studies of morphology, chemical classification and phylogenetic analysis based on the 16s rrna sequences among the four type strains of the genus actinobispora and type strains of related ... | 1999 | 10319514 |
| amycolatopsis thermoflava sp. nov., a novel soil actinomycete from hainan island, china. | a soil isolate, which had been assigned to the genus nocardia, was shown to have properties consistent with its classification in the genus amycolatopsis. an almost complete nucleotide sequence of the 16s rdna of the strain was determined following cloning and sequencing of the amplified gene. the sequence was aligned with those available for members of the family pseudonocardiaceae and related taxa and phylogenetic trees were inferred using three tree-making algorithms. the organism consistentl ... | 1999 | 10555314 |
| identification of amycolatopsis sp. strain hr167 genes, involved in the bioconversion of ferulic acid to vanillin. | the gene loci ech, encoding enoyl-coa hydratase/aldolase, and fcs, encoding an unusual feruloyl-coa synthetase, which are involved in the bioconversion of ferulic acid to vanillin by the gram-positive bacterium amycolatopsis sp. strain hr167, were localized on a 4,000 bp psti fragment (p40). the nucleotide sequence of p40 was determined, revealing open reading frames of 864 bp and 1,476 bp, representing ech and fcs, respectively. the deduced amino acid sequences of ech exhibited 62% amino acid i ... | 2000 | 11152072 |
| amycolatopsis sacchari sp. nov., a moderately thermophilic actinomycete isolated from vegetable matter. | the taxonomic position of a group of moderately thermophilic actinomycetes isolated from vegetable matter was determined using a suite of genotypic and phenotypic properties. the organisms were found to share a range of chemical and morphological markers typical of members of the genus amycolatopsis. a representative of the group, strain k24t, formed a distinct phyletic line within the range of variation occupied by the genus amycolatopsis in the 16s rdna tree. the strains have many phenotypic p ... | 2001 | 11211259 |
| comparative chemotherapeutic efficacy of balhimycin, desgluco-balhimycin against experimental mssa and mrsa infection in mice. | balhimycin and desglucobalhimycin are glycopeptide antibiotics isolated from an amycolatopsis spp during the search for novel antibacterials against mrsa from the natural product screening at the research centre of formerly hoechst india ltd. in bombay, india. both compounds show excellent in vitro activity against methicillin sensitive and resistant staphylococcus aureus (mssa, mrsa). both compounds were also found to be active against a number of mrsa strain in the animal studies. the activiti ... | 2000 | 11215311 |
| molecular analysis and heterologous expression of the gene encoding methylmalonyl-coenzyme a mutase from rifamycin sv-producing strain amycolatopsis mediterranei u32. | the conversion of succinyl-coenzyme a (coa) into methylmalonyl-coa, catalyzed by adenosylcobalamin-dependent methylmalonyl-coa mutase (mcm), represents an important source of building blocks for rifamycin sv biosynthesis. the structural gene for mcm from rifamycin sv-producing strain amycolatopsis mediterranei u32 was isolated by using a heterologous gene probe encoding the mcm of streptomyces cinnamonesis. a 7.8-kbp fragment was sequenced and four complete open reading frames (orfs) and two inc ... | 1999 | 10813025 |
| a novel transmembrane serine/threonine protein kinase gene from a rifamycin sv-producing amycolatopsis mediterranei u32. | genomic dna sequencing in the vicinity of methylmalonyl-coa mutase gene (mutab) from a rifamycin sv-producing amycolatopsis mediterranei u32 allowed us to clone, sequence, and identify a gene encoding a novel serine/threonine protein kinase (amk). the sequence contains a complete orf of 1821 base pairs encoding a predicted protein of 606 amino acids in length. the n-terminal domain of the protein shows significant homology to the catalytic domain of other protein kinases from both prokaryotic an ... | 2000 | 10848993 |
| a polyketide synthase in glycopeptide biosynthesis: the biosynthesis of the non-proteinogenic amino acid (s)-3,5-dihydroxyphenylglycine. | balhimycin, a vancomycin-type antibiotic from amycolatopsis mediterranei, contains the unusual amino acid (s)-3,5-dihydroxyphenylglycine (dpg), with an acetate-derived carbon backbone. after sequence analysis of the biosynthetic gene cluster, one gene, dpga, for a predicted polyketide synthase (pks) was identified, sharing 20-30% identity with plant chalcone synthases. inactivation of dpga resulted in loss of balhimycin production, and restoration was achieved by supplementation with 3,5-dihydro ... | 2001 | 11495926 |
| [increase in eremomycin production by regeneration and uv-irradiation of amycolatopsis orientalis subsp. eremomycini protoplasts]. | protoplast regeneration of amycolatopsis orientalis subsp. eremomycini producing eremomycin leads to the change of cultural and morphological properties as well as synthesis of secondary metabolites. formation of plus-variants with enchanced antibiotic production was promoted by uv-irradiation of protoplasts. these plus-variants can be successfully used for repeating protoplasting--uv-irradiation of protoplasts with further increasing of the strain productivity. finally activity of the initial a ... | 2001 | 11548282 |
| development of three different gene cloning systems for genetic investigation of the new species amycolatopsis japonicum mg417-cf17, the ethylenediaminedisuccinic acid producer. | for the first time gene cloning systems have been developed for amycolatopsis japonicum. direct transformation, polyethyleneglycol (peg) induced protoplast transformation and conjugal transfer was established for a. japonicum mg417-cf17, the ethylenediaminedisuccinic acid (edds) producer. the direct transformation procedure was modified to introduce dna. the most important parameter for an efficient dna uptake was the age of the culture. using of mycelium from 36-h old cultures resulted in the h ... | 2001 | 11640989 |
| cloning and partial characterization of the putative rifamycin biosynthetic gene cluster from the actinomycete amycolatopsis mediterranei dsm 46095. | the actinomycete amycolatopsis mediterranei produces the commercially and medically important polyketide antibiotic rifamycin, which is widely used against mycobacterial infections. the rifamycin biosynthetic (rif) gene cluster has been isolated, cloned and characterized from a. mediterranei s699 and a. mediterranei lbga 3136. however, there are several other strains of a. mediterranei which also produce rifamycins. in order to detect the variability in the rif gene cluster among these strains, ... | 2001 | 11716212 |
| induction of microbial secondary metabolism. | precursors often stimulate production of secondary metabolites either by increasing the amount of a limiting precursor, by inducing a biosynthetic enzyme (synthase) or both. these are usually amino acids but other small molecules also function as inducers. the most well-known are the auto-inducers which include gamma-butyrolactones (butanolides) of the actinomycetes, n-acylhomoserine lactones of gram-negative bacteria, oligopeptides of gram-positive bacteria, and b-factor (3'-[1-butylphosphoryl] ... | 1998 | 10943372 |
| purification and characterization of an extracellular poly(l-lactic acid) depolymerase from a soil isolate, amycolatopsis sp. strain k104-1. | poly(l-lactic acid) (pla)-degrading amycolatopsis sp. strains k104-1 and k104-2 were isolated by screening 300 soil samples for the ability to form clear zones on the pla-emulsified mineral agar plates. both of the strains assimilated >90% of emulsified 0.1% (wt/vol) pla within 8 days under aerobic conditions. a novel pla depolymerase with a molecular weight of 24,000 was purified to homogeneity from the culture supernatant of strain k104-1. the purified enzyme degraded high-molecular-weight pla ... | 2001 | 11133465 |
| glycopeptide antibiotic biosynthesis: enzymatic assembly of the dedicated amino acid monomer (s)-3,5-dihydroxyphenylglycine. | four proteins, dpga-d, required for the biosynthesis by actinomycetes of the nonproteinogenic amino acid monomer (s)-3,5-dihydroxyphenylglycine (dpg), that is a crosslinking site in the maturation of vancomycin and teicoplanin antibiotic scaffolds, were expressed in escherichia coli, purified in soluble form, and assayed for enzymatic activity. dpga is a type iii polyketide synthase, converting four molecules of malonyl-coa to 3,5-dihydroxyphenylacetyl-coa (dpa-coa) and three free coenzyme a (co ... | 2001 | 11752437 |
| the vancomycin biosynthetic pathway is induced in oxygen-limited amycolatopsis orientalis (atcc 19795) cultures that do not produce antibiotic. | vancomycin biosynthetic capacity was stimulated in oxygen-limited bioreactor culture (6.4% dot) of amycolatopsis orientalis, coinciding with a down-regulation of the culture growth and protein synthesis rates. however no vancomycin was detected. atp production was similar in oxygen-limited and oxygen-sufficient cultures (400-150 µmole(atp). g(biomass)(-1)). our findings suggest a critical requirement for oxygen flux through the vancomycin biosynthetic pathway, which is only met under nutrient-li ... | 2000 | 10978772 |
| expression and purification of the rifamycin amide synthase, riff, an enzyme homologous to the prokaryotic arylamine n-acetyltransferases. | the assembly of the polyketide backbone of rifamycin b by the type i rifamycin polyketide synthase, encoded by the rifa-rife genes, is terminated by the product of the riff gene, an amide synthase that releases the completed undecaketide as its macrocyclic lactam. the sequence of the riff protein from amycolatopsis mediterranei shows 26% identity and 40% homology with the members of the arylamine n-acetyltransferase (nat) family of proteins. based on the homology of the primary structures and th ... | 2002 | 11812235 |
| glycopeptide biosynthesis in amycolatopsis mediterranei dsm5908: function of a halogenase and a haloperoxidase/perhydrolase. | glycopeptides are important clinical emergency antibiotics consisting of a glycosylated and chlorinated heptapeptide backbone. the understanding of the biosynthesis is crucial for development of new glycopeptides. with balhimycin as a model system, this work focuses on the investigation of the putative halogenase gene (bhaa) and the putative haloperoxidase/perhydrolase gene (bhp) of the balhimycin biosynthesis gene cluster. an in-frame deletion mutant in the haloperoxidase/perhydrolase gene bhp ... | 2002 | 11880037 |
| kinetic analysis of ppi-dependent phosphofructokinase from porphyromonas gingivalis. | we have previously cloned the gene encoding a pyrophosphate-dependent phosphofructokinase (pfk), designated pgpfk, from porphyromonas gingivalis, an oral anaerobic bacterium implicated in advanced periodontal disease. in this study, recombinant pgpfk was purified to homogeneity, and biochemically characterized. the apparent k(m) value for fructose 6-phosphate was 2.2 mm, which was approximately 20 times higher than that for fructose 1,6-bisphosphate. the value was significantly greater than any ... | 2002 | 11886747 |
| [isolation of actinomycetes from soil using extremely high frequency radiation]. | a new method employing extremely high frequencies (ehfs) is proposed for the selective isolation of actinomycetes from soil. the pretreatment of soil suspensions with ehf wavelengths of 5.6 and 7.1 mm led to a nonselective isolation of actinomycetes. at the same time, the irradiation of soil suspensions within wavelength bands of 3.8-5.8 and 8-11.5 mm considerably augmented the total number of isolated actinomycetes and increased the fraction of the isolated rare genera by 2 and 7 times, respect ... | 2002 | 11910800 |
| nicotinoprotein (nadh-containing) alcohol dehydrogenase from rhodococcus erythropolis dsm 1069: an efficient catalyst for coenzyme-independent oxidation of a broad spectrum of alcohols and the interconversion of alcohols and aldehydes. | extracts from benzyl-alcohol-grown rhodococcus erythropolis dsm 1069 showed nad(p)-independent, n,n-dimethyl-4-nitrosoaniline (ndma)-dependent alcohol dehydrogenase activity. the enzyme exhibiting this activity was purified to homogeneity and characterized. it appears to be a typical nicotinoprotein as it contains tightly bound nadh acting as cofactor instead of coenzyme. other characteristics indicate that it is highly similar to the known nicotinoprotein alcohol dehydrogenase (np-adh) from amy ... | 2000 | 10784035 |
| sequence analysis and expression of the aspartokinase and aspartate semialdehyde dehydrogenase operon from rifamycin sv-producing amycolatopsis mediterranei. | a approximately 4.8 kb kpni fragment, from the upstream region of the methylmalonyl-coa mutase gene (mutab) of rifamycin sv-producing amycolatopsis mediterranei, was cloned and partially sequenced. codon preference analysis showed three complete orfs. orf2 is internal to orf1, and encodes a polypeptide corresponding to 172 amino acids, whereas orf1 encodes a polypeptide of 421 amino acids. they were identified as the encoding genes of aspartokinase alpha- and beta-subunits by comparing the amino ... | 1999 | 10521665 |
| structure of actinotetraose hexatiglate, a unique glucotetraose from an actinomycete bacterium. | an actinomycete strain a499 belonging to the genera amycolatopsis or amycolata isolated from a western australian soil sample produced the cyclic decapeptide antibiotic quinaldopeptin (1), together with the actinotetraose hexatiglate (2), the hexa-ester of a novel non-reducing glucotetraose. | 1998 | 10048568 |
| optical spectroscopy of nicotinoprotein alcohol dehydrogenase from amycolatopsis methanolica: a comparison with horse liver alcohol dehydrogenase and udp-galactose epimerase. | the nadh absorbance spectrum of nicotinoprotein (nadh-containing) alcohol dehydrogenase from amycolatopsis methanolica has a maximum at 326 nm. reduced enzyme-bound pyridine dinucleotide could be reversibly oxidized by acetaldehyde. the fluorescence excitation spectrum for nadh bound to the enzyme has a maximum at 325 nm. upon excitation at 290 nm, energy transfer from tryptophan to enzyme-bound nadh was negligible. the fluorescence emission spectrum (excitation at 325 nm) for nadh bound to the ... | 1998 | 9485460 |
| amycolatopsis albidoflavus sp. nov. | the generic position of an actinomycete strain, 'pseudonocardia sp.' imsnu 22139, was investigated by the phylogenetic analysis of 16s rdna sequence. comparative studies of 16s rdna sequences indicated that this organism consistently formed a distinct clade within the radiation of the genus amycolatopsis of the family pseudonocardiaceae. this organism was also found to have chemotaxonomic properties consistent with those of the genus amycolatopsis, which were represented by a type iv cell wall ( ... | 2001 | 11321110 |
| characterization of the ribosomal rrnd operon of the cephamycin-producer 'nocardia lactamdurans' shows that this actinomycete belongs to the genus amycolatopsis. | the cephamycin producer strain 'nocardia lactamdurans' contains four ribosomal rna (rrn) operons. one of them (rrnd) was cloned from a dna library in the bifunctional cosmid pjar4. a 2229 bp region of rrnd has been sequenced. the 'n. lactamdurans' rrnd operon maintains the canonical order 5'-16s-23s-5s-3'. four of the consensus gürtler-stanisch sequences were found in the 16s rrna gene and a fifth one in the sequenced 5' region of the 23s rrna gene. the anti shine-dalgarno sequence of 'n. lactam ... | 2000 | 10879974 |
| biosynthesis of 1-deoxy-1-imino-d-erythrose 4-phosphate: a defining metabolite in the aminoshikimate pathway. | with respect to the source of the nitrogen atom incorporated into the aminoshikimate pathway, d-erythrose 4-phosphate has been proposed to undergo a transamination reaction resulting in formation of 1-deoxy-1-imino-d-erythrose 4-phosphate. condensation of this metabolite with phosphoenolpyruvate catalyzed by aminodahp synthase would then hypothetically form the 4-amino-3,4-dideoxy-d-arabino-heptulosonic acid 7-phosphate (aminodahp), which is the first committed intermediate of the aminoshikimate ... | 2002 | 11804477 |
| chromosome topology and genome size of selected actinomycetes species. | information about the genome organization of actinomycetes species is restricted to a few genera: corynebacterium, mycobacterium, rhodococcus, saccharopolyspora and streptomyces. streptomyces species and saccharopolyspora erythraea were shown to contain a single linear 8 mb chromosome. in contrast, the corynebacterium, mycobacterium and rhodococcus species studied were demonstrated to possess a smaller (3 mb-6.5 mb) single circular chromosome. to investigate whether linear chromosome topology an ... | 2000 | 11386344 |
| [the application of succession analysis in combination with extremely high-frequency irradiation to the selective isolation of actinomycetes from soil]. | a new method employing succession analysis and extremely high-frequency (ehf) irradiation is proposed for the selective isolation of actinomycetes from soil. total actinomycetes were efficiently isolated from soil suspensions irradiated in the wavelength band 4.6-5.8 mm on the 14th and 45th days of succession initiated by soil wetting and from soil suspensions irradiated in the wavelength band 8-11.5 mm on the 7th day of succession. the rare actinomycete genera actinomadura, micromonospora, nono ... | 2003 | 12698804 |
| teicoplanin biosynthesis genes in actinoplanes teichomyceticus. | the genetic determinants for the biosynthesis of the glycopeptide antibiotic teicoplanin were identified. in order to isolate the corresponding gene cluster, oligonucleotides derived from highly conserved motifs in peptide synthetases were used. these synthetic probes, and gene fragments derived from the balhimycin gene cluster of amycolatopsis mediterranei, led to the identification of the likely teicoplanin gene cluster centered on a region of ca. 110 kb from the genome of actinoplanes teichom ... | 2000 | 11386360 |
| structure of the ask-asd operon and formation of aspartokinase subunits in the cephamycin producer 'amycolatopsis lactamdurans'. | the first two genes of the lysine pathway are closely linked forming a transcriptional operon in the cephamycin producer 'amycolatopsis lactamdurans'. the asd gene, encoding the enzyme aspartic semialdehyde dehydrogenase, has been cloned by complementation of escherichia coli asd mutants. it encodes a protein of 355 aa with a deduced m(r) of 37109. the ask gene encoding the aspartokinase (ask) is located upstream of the asd gene as shown by determination of ask activity conferred to e. coli tran ... | 2001 | 11390685 |
| an eukaryotic-type serine/threonine protein kinase involved in the carbon source-dependent pigment biosynthesis in amycolatopsis mediterranei u32. | the structural gene, pkma, was cloned and sequenced from a rifamycin sv-producing amycolatopsis mediterranei u32 strain. the n-terminal portion of the deduced amino acid sequence of pkma showed significant similarity to the family of serine/threonine protein kinases. it contains all the structural features which are highly conserved in protein kinases, including the gly-x-gly-x-x-gly motif of atp binding and the essential amino acids known to be important for the recognition of the correct hydro ... | 2001 | 11394886 |
| amycolatopsis eurytherma sp. nov., a thermophilic actinomycete isolated from soil. | the taxonomic positions of two thermophilic actinomycetes isolated from soil were established in a polyphasic taxonomic study. the organisms were shown to have phenotypic properties typical of members of the genus amycolatopsis and formed a distinct phyletic line in the amycolatopsis methanolica 16s rdna subclade. they also had many phenotypic properties in common and formed a genomic species that was closely related to, albeit distinct from, the type strain of a. methanolica. a range of phenoty ... | 2002 | 12054254 |
| new insights into rifamycin b biosynthesis: isolation of proansamycin b and 34a-deoxy-rifamycin w as early macrocyclic intermediates indicating two separated biosynthetic pathways. | proansamycin b, the formerly postulated intermediate of rifamycin b biosynthesis, was isolated from cultures of the amycolatopsis mediterranei mutant f1/24. the structure was determined using uv, ir, nmr and ms techniques. biotransformation studies demonstrate that proansamycin b is an intermediate of a shunt pathway, a 8-deoxy variant, of rifamycin b biosynthesis leading to 8-deoxy-rifamycin b as the final product. in addition, 34a-deoxy-rifamycin w, the direct precursor of rifamycin w, could b ... | 2002 | 12061548 |
| purification, crystallization and preliminary structural studies of dtdp-4-keto-6-deoxy-glucose-5-epimerase (evad) from amycolatopsis orientalis, the fourth enzyme in the dtdp-l-epivancosamine biosynthetic pathway. | the vancomycin class of antibiotics is regarded as the last line of defence against gram-positive bacteria. the compounds used clinically are very complex organic molecules and are made by fermentation. the biosynthesis of these is complex and fascinating. its study holds out the prospect of utilizing genetic engineering of the enzymes in the pathway in order to produce novel vancomycin analogues. in part, this requires detailed structural insight into substrate specificity as well as the enzyme ... | 2002 | 12077451 |
| mutational analysis and reconstituted expression of the biosynthetic genes involved in the formation of 3-amino-5-hydroxybenzoic acid, the starter unit of rifamycin biosynthesis in amycolatopsis mediterranei s699. | to investigate a novel branch of the shikimate biosynthesis pathway operating in the formation of 3-amino-5-hydroxybenzoic acid (ahba), the unique biosynthetic precursor of rifamycin and related ansamycins, a series of target-directed mutations and heterologous gene expressions were investigated in amycolatopsis mediterranei and streptomyces coelicolor. the genes involved in ahba formation were inactivated individually, and the resulting mutants were further examined by incubating the cell-free ... | 2001 | 11278540 |
| tandem action of glycosyltransferases in the maturation of vancomycin and teicoplanin aglycones: novel glycopeptides. | the glycopeptides vancomycin and teicoplanin are clinically important antibiotics. the carbohydrate portions of these molecules affect biological activity, and there is great interest in developing efficient strategies to make carbohydrate derivatives. to this end, genes encoding four glycosyltransferases, gtfb, c, d, e, were subcloned from amycolatopsis orientalis strains that produce chloroeremomycin (gtfb, c) or vancomycin (gtfd, e) into escherichia coli. after expression and purification, ea ... | 2001 | 11294642 |
| crystal structure of oxyb, a cytochrome p450 implicated in an oxidative phenol coupling reaction during vancomycin biosynthesis. | gene-inactivation studies point to the involvement of oxyb in catalyzing the first oxidative phenol coupling reaction during glycopeptide antibiotic biosynthesis. the oxyb gene has been cloned and sequenced from the vancomycin producer amycolatopsis orientalis, and the hemoprotein has been produced in escherichia coli, crystallized, and its structure determined to 1.7-a resolution. oxyb gave uv-visible spectra characteristic of a p450-like hemoprotein in the low spin ferric state. after reductio ... | 2002 | 12207020 |
| kanosamine biosynthesis: a likely source of the aminoshikimate pathway's nitrogen atom. | the biosynthetic source of the nitrogen atom incorporated into the aminoshikimate pathway has remained a question for some time. 3-amino-3-deoxy-d-fructose 6-phosphate has previously been demonstrated to be a precursor to 4-amino-3,4-dideoxy-d-arabino-heptulosonic acid 7-phosphate and 3-amino-5-hydroxybenzoic acid via the inferred intermediacy of 1-deoxy-1-imino-d-erythrose 4-phosphate in amycolatopsis mediterranei cell-free extract. this investigation examines the possibility that the natural p ... | 2002 | 12207504 |
| the first reported case of equine nocardioform placentitis in south africa. | since the late 1980s a distinct form of focally-extensive mucoid to mucopurulent uterine body chronic placentitis,caused by nocardioform organisms, hasbeen recognised in horses in the usa state of kentucky and possibly in other areas. this disease has led to increasing numbers of foal losses from late abortions, still-births, prematurity, or early neonatal deaths. the foals are usually not infected, but may be small or emaciated. modes of infection and transmission are as yet unknown. nocardia s ... | 2001 | 12219921 |
| molecular and biochemical characterization of a novel two-component signal transduction system, amra- amka, involved in rifamycin sv production in amycolatopsis mediterranei u32. | two-component and phosphorelay signal transduction systems are the major means by which bacteria recognize and respond to a variety of environmental stimuli. although several model systems, including sporulation in bacillus subtilis and chemotaxis in escherichia coli, have been extensively studied, the two-component signal transduction systems in industrially important actinomycetes are not well studied. we report the molecular and biochemical characterization of a novel two-component signal sys ... | 2002 | 12375106 |
| moea, an enzyme in the molybdopterin synthesis pathway, is required for rifamycin sv production in amycolatopsis mediterranei u32. | rifamycin sv contains one amide nitrogen atom at its c(7)n moiety. earlier labeling studies suggested that nitrogen might be incorporated from a pathway involved in a molybdenum-dependent nitrate reductase. however, no genetic evidence is available thus far. the structural gene moea, which is involved in molybdopterin synthesis in various organisms, has been cloned from rifamycin sv-producing amycolatopsis mediterranei strain u32. the amino acid sequence deduced from the moea gene showed signifi ... | 2002 | 12382055 |
| different physiological roles of atp- and pp(i)-dependent phosphofructokinase isoenzymes in the methylotrophic actinomycete amycolatopsis methanolica. | cells of the actinomycete amycolatopsis methanolica grown on glucose possess only a single, exclusively pp(i)-dependent phosphofructokinase (pp(i)-pfk) (a. m. c. r. alves, g. j. w. euverink, h. j. hektor, j. van der vlag, w. vrijbloed, d.h.a. hondmann, j. visser, and l. dijkhuizen, j. bacteriol. 176:6827-6835, 1994). when this methylotrophic bacterium is grown on one-carbon (c(1)) compounds (e.g., methanol), an atp-dependent phosphofructokinase (atp-pfk) activity is specifically induced, complet ... | 2001 | 11717283 |
| optimization of fermentation conditions for production of glycopeptide antibiotic vancomycin by amycolatopsis orientalis. | glycopeptides produced by streptomyces species are the drugs used against beta-lactam drug-resistant staphylococcal infections, and vancomycin is important among them. increased prevalence of resistant strains increased the usage of vancomycin worldwide and also promoted attempts for indigenous production. the optimum process conditions ph, temperature, inoculum size, agitation, and aeration for vancomycin production by amycolatopsis orientalis were evaluated, statistically analyzed, and the res ... | 2002 | 12396140 |
| combinatorial glycosylation of glycopeptide antibiotics. | the glycosyltransferases gtfe and gtfd from the vancomycin producer amycolatopsis orientalis have promiscuous substrate and ndp-sugar specificities. they have been used to generate novel glycopeptide antibiotics containing the heptapeptide scaffolds of vancomycin and teichoplanin. | 2002 | 12498878 |
| isolation of a microorganism capable of degrading poly-(l-lactide). | the isolation of poly-(l-lactide) (pla)-degrading microorganisms was investigated. a pla-degrading actinomycete, strain no. 3118, was isolated and tentatively identified as a member of the genus amycolatopsis. the optimum conditions for degradation of pla were 43 degrees c at about ph 7 in a mineral salt medium with a low concentration of organic nutrients (0.002% yeast extract). the original shape of pla film (mw=2.3x10(5) after sterilization, 20 &mgr;m thick) disappeared within 2 weeks. lactic ... | 1999 | 12501367 |
| biosynthesis of rifamycin sv by amycolatopsis mediterranei mtcc17 in solid cultures. | studies were performed on the production of rifamycin sv, an ansamycin compound, extensively used for curing tuberculosis, leprosy and several other mycobacterial infections, using a strain of amycolatopsis mediterranei mtcc17 in solid cultures. wheat bran was employed as a solid substrate. the culture produced 4 g of rifamycin sv/kg of substrate. pre-treatment of the substrate with dilute hcl was found to increase the yield of rifamycin sv by 300% (from 4 to 12 g x kg of substrate(-1)). various ... | 2003 | 12546705 |
| identification of a novel mannose-capped lipoarabinomannan from amycolatopsis sulphurea. | the genus amycolatopsis is a member of the phylogenetic group nocardioform actinomycetes, which also includes the genus mycobacterium. members of this group have a characteristic cell envelope structure, dominated by various complex lipids and polysaccharides. amongst these, lipoglycans are of particular interest since mycobacterial lipoarabinomannans are important immunomodulatory molecules. in this study we report the isolation and structural characterization of amycolatopsis sulphurea lipoara ... | 2003 | 12620092 |
| isolation and characterization of 27-o-demethylrifamycin sv methyltransferase provides new insights into the post-pks modification steps during the biosynthesis of the antitubercular drug rifamycin b by amycolatopsis mediterranei s699. | the gene rif orf14 in the rifamycin biosynthetic gene cluster of amycolatopsis mediterranei s699, producer of the antitubercular drug rifamycin b, encodes a protein of 272 amino acids identified as an adomet: 27-o-demethylrifamycin sv methyltransferase. frameshift inactivation of rif orf14 generated a mutant of a. mediterranei s699 that produces no rifamycin b, but accumulates 27-o-demethylrifamycin sv (dmrsv) as the major new metabolite, together with a small quantity of 27-o-demethyl-25-o-desa ... | 2003 | 12623077 |
| nonribosomal biosynthesis of vancomycin-type antibiotics: a heptapeptide backbone and eight peptide synthetase modules. | during analysis of the recently identified gene cluster for the glycopeptide antibiotic balhimycin, produced by amycolatopsis mediterranei dsm 5908, novel genes were identified and characterized in detail. the gene products of four of the identified genes (bpsa, bpsb, bpsc and bpsd) are nonribosomal peptide synthetases (nrpss); one (orf1-protein) shows similarities to small proteins associated with several nrpss without an assigned function. bpsa and bpsb are composed of three modules each (modu ... | 2002 | 11932455 |
| efficient isolation of total rna from antibiotic-producing bacterium amycolatopsis mediterranei. | rna extraction from antibiotic-producing actinomycetes can be a difficult and time-consuming process due to their special peptidoglycans cell wall composition and the short life of rna. hence, the rapidity of cellular lysis and complete inhibition of rnase are of particular importance for isolating intact rna of high quality. the genus of amycolatopsis mediterranei produces many clinically important antibiotics, such as rifamycin and vancomycin; however, the available methods for bacterial rna i ... | 2002 | 12133611 |
| isolation and characterization of actinomycetes from brazilian tropical soils. | actinomycetes have been isolated from three brazilian tropical soils. the dispersion and differential centrifugation procedure revealed count values 1.5 to 5.0 times greater than those obtained by the conventional dilution plate technique for all soils and media tested. eighteen strains, promising for biotechnological applications, were submitted to chemotaxonomic procedures and numerical taxonomy for identification. two were identified as amycolatopsis orientalis, one as streptomyces misakiensi ... | 2001 | 11297360 |
| development of cloning vectors and transformation methods for amycolatopsis. | the genus amycolatopsis is of industrial importance, as its species are known to produce commercial antibiotics. it belongs to the family pseudonocardiaceae and has an eventful taxonomic history. initially strains were identified as streptomyces, then later as nocardia. however, based on biochemical, morphological and molecular features, the genus amycolatopsis, containing seventeen species, was created. the development of molecular genetic techniques for this group has been slow. the scarcity o ... | 2003 | 12687493 |
| engineered biosynthesis of an ansamycin polyketide precursor in escherichia coli. | ansamycins such as rifamycin, ansamitocin, and geldanamycin are an important class of polyketide natural products. their biosynthetic pathways are especially complex because they involve the formation of 3-amino-5-hydroxybenzoic acid (ahba) followed by backbone assembly by a hybrid nonribosomal peptide synthetase/polyketide synthase. we have reconstituted the ability to synthesize 2,6-dimethyl-3,5,7-trihydroxy-7-(3'-amino-5'-hydroxyphenyl)-2,4-heptadienoic acid (p8/1-og), an intermediate in rifa ... | 2003 | 12888623 |
| amycolatopsis kentuckyensis sp. nov., amycolatopsis lexingtonensis sp. nov. and amycolatopsis pretoriensis sp. nov., isolated from equine placentas. | actinomycete strains isolated from lesions on equine placentas from two horses in kentucky and one in south africa were subjected to a polyphasic taxonomic study. chemotaxonomic and morphological characteristics indicated that the isolates are members of the genus amycolatopsis: on the basis of phylogenetic analysis of 16s rdna sequences, the isolates are related most closely to amycolatopsis mediterranei. physiological characteristics of these strains indicated that they do not belong to a. med ... | 2003 | 13130055 |
| gamma-butyrolactone autoregulators and receptor proteins in non- streptomyces actinomycetes producing commercially important secondary metabolites. | the presence of gamma-butyrolactone autoregulators and their receptor proteins were investigated in five representative strains of non- streptomyces actinomycetes producing commercially important secondary metabolites. ethyl acetate extracts of culture were assayed using wild-type s. virginiae for virginiae butanolide, s. lavendulae fri-5 for im-2, and s. griseus hh1 for a-factor. actinoplanes teichomyceticus and amycolatopsis mediterranei were shown to produce autoregulators. corresponding auto ... | 2003 | 14523609 |
| [establishment of gene replacement/disruption system through homologous recombination in amycolatopsis mediterranei u32]. | a gene replacement/disruption system of amycolatopsis mediterranei u32 was developed based on the established electroporation conditions as well as appropriate selective markers. through two-step selection, ahbas gene in u32 was replaced by a promoterless alpha-amylase gene constructed on the plasmid pdk110 of e. coli. the first single-crossover and the second double-crossover frequencies were approximately 0.5%-0.7% and 2%, respectively. denaturation of the plasmid pdk110 increased the integrat ... | 2002 | 12385238 |
| meaa, a putative coenzyme b12-dependent mutase, provides methylmalonyl coenzyme a for monensin biosynthesis in streptomyces cinnamonensis. | the ratio of the major monensin analogs produced by streptomyces cinnamonensis is dependent upon the relative levels of the biosynthetic precursors methylmalonyl-coenzyme a (coa) (monensin a and monensin b) and ethylmalonyl-coa (monensin a). the meaa gene of this organism was cloned and sequenced and was shown to encode a putative 74-kda protein with significant amino acid sequence identity to methylmalonyl-coa mutase (mcm) (40%) and isobutyryl-coa mutase (icm) large subunit (36%) and small subu ... | 2001 | 11222607 |
| inhibition of nicotinoprotein (nad+-containing) alcohol dehydrogenase by trans-4-(n,n-dimethylamino)-cinnamaldehyde binding to the active site. | ethanol oxidation by nicotinoprotein alcohol dehydrogenase (np-adh) from the bacterium amycolatopsis methanolica is inhibited by trans-4-(n,n-dimethylamino)-cinnamaldehyde through direct binding to the catalytic zinc ion in a substrate-like geometry. this binding is accompanied by a characteristic red shift of the aldehyde absorbance from 398 nm to 467 nm. np-adh is structurally related to mammalian adh class i, and a model of np-adh shows how the cinnamaldehyde derivative can be accommodated in ... | 2003 | 14690248 |
| evolution of enzymatic activity in the enolase superfamily: functional studies of the promiscuous o-succinylbenzoate synthase from amycolatopsis. | o-succinylbenzoate synthase (osbs) from amycolatopsis, a member of the enolase superfamily, catalyzes the mn2+-dependent exergonic dehydration of 2-succinyl-6r-hydroxy-2,4-cyclohexadiene-1r-carboxylate (shchc) to 4-(2'-carboxylphenyl)-4-oxobutyrate (o-succinylbenzoate or osb) in the menaquinone biosynthetic pathway. this enzyme first was identified as an n-acylamino acid racemase (naaar), with the optimal substrates being the enantiomers of n-acetyl methionine. this laboratory subsequently disco ... | 2004 | 14705949 |
| amycolatopsis decaplanina sp. nov., a novel member of the genus with unusual morphology. | strain dsm 44594t, which produces the glycopeptide antibiotic decaplanin, is a member of the genus amycolatopsis based on 16s rrna gene sequence analysis and chemotaxonomic properties. it is the first member of this genus that is reported to form pseudosporangia, which resemble those of members of the genus kibdelosporangium. phylogenetically, the novel taxon is related to amycolatopsis orientalis, amycolatopsis lurida, amycolatopsis azurea, amycolatopsis japonica and amycolatopsis keratiniphila ... | 2004 | 14742486 |
| reclassification of amycolatopsis orientalis subsp. lurida lechevalier et al. 1986 as amycolatopsis lurida sp. nov., comb. nov. | amycolatopsis orientalis subsp. lurida dsm 43134t differs significantly from the type strain of a. orientalis, a. orientalis subsp. orientalis dsm 40040t, and from other species of the genus in genomic and metabolic properties. its elevation to species status as amycolatopsis lurida sp. nov., comb. nov. is justified. | 2004 | 14742491 |
| improvement of industry-applied rifamycin b-producing strain, amycolatopsis mediterranei, by rational screening. | an industrially applied rifamycin b-producing strain, amycolatopsis mediterranei xc 1-02, was used for further screening. a special mutation and screening procedure was adopted to select a strain, which can alleviate the inhibition caused by both aromatic amino acid and p-hydroxybenzoic acid in the pathway of rifamycin b biosynthesis as well as enhance the production of propionate, one of the precursors of rifamycin b biosynthesis. by the above methods, a strain a. mediterranei xc 9-25 was obtai ... | 2002 | 12682871 |
| role of the active site cysteine of dpga, a bacterial type iii polyketide synthase. | dpga is a bacterial type iii polyketide synthase (pks) that decarboxylates and condenses four malonyl-coa molecules to produce 3,5-dihydroxyphenylacetyl-coa (dpa-coa) in the biosynthetic pathway to 3,5-dihydroxyphenylglycine, a key nonproteinogenic residue in the vancomycin family of antibiotics. dpga has the conserved catalytic triad of cys/his/asn typical of type iii pks enzymes, and has been assumed to use cys160 as the catalytic nucleophile to create a series of elongating acyl-s-enzyme inte ... | 2004 | 14744141 |
| (de)regulation of key enzyme steps in the shikimate pathway and phenylalanine-specific pathway of the actinomycete amycolatopsis methanolica. | prephenate dehydratase (pdt), chorismate mutase (cm) and 3-deoxy-d-arabino-7-heptulosonate 7-phosphate (dahp) synthase are key regulatory enzymes in aromatic amino acid biosynthesis in the actinomycete amycolatopsis methanolica. deregulated, feedback-control-resistant mutants were isolated by incubation of a. methanolica on glucose mineral agar containing the toxic analogue p-fluoro-dl-phenylalanine (pfphe). several of these mutants had completely lost pdt sensitivity to phe inhibition and tyr a ... | 2003 | 14600244 |
| stability of plasmid pa387 derivatives in amycolatopsis mediterranei producing rifamycin. | genetic studies on the biosynthesis of rifamycins in producer strains such as amylcolaptopsis mediterranei u-32 are severely hampered by the availability of efficient transformation procedures and stable plasmid vectors. using an efficient electroporation procedure we have studied the replication and stability of a pa387 derivative, pdxm32. this plasmid confers enhanced plasmid stability and copy number compared to pa387 derivatives commonly used as cloning vectors in a. mediterranei. deletion d ... | 2003 | 14584922 |
| amycolatopsis palatopharyngis sp. nov., a potentially pathogenic actinomycete isolated from a human clinical source. | the taxonomic position of an actinomycete, strain 1bdz(t), isolated from a clinical human source was determined using a polyphasic approach. phylogenetic analysis based on almost complete 16s rdna sequences showed that this organism consistently formed a distinct line with the amycolatopsis methanolica subclade within the genus amycolatopsis, and shared moderately low 16s rdna similarity (<96.5 %) with other species. the organism was also found to have chemical and morphological properties typic ... | 2004 | 15023943 |
| optimization of rifamycin b fermentation in shake flasks via a machine-learning-based approach. | rifamycin b is an important polyketide antibiotic used in the treatment of tuberculosis and leprosy. we present results on medium optimization for rifamycin b production via a barbital insensitive mutant strain of amycolatopsis mediterranei s699. machine-learning approaches such as genetic algorithm (ga), neighborhood analysis (na) and decision tree technique (dt) were explored for optimizing the medium composition. genetic algorithm was applied as a global search algorithm while na was used for ... | 2004 | 15052640 |
| synthesis of aminoshikimic acid. | 5-amino-5-deoxyshikimic acid (aminoshikimic acid) was synthesized from glucose using recombinant amycolatopsis mediterranei and also synthesized by a tandem, two-microbe route employing bacillus pumilus and recombinant escherichia coli. | 2004 | 15128242 |
| kigamicins, novel antitumor antibiotics. i. taxonomy, isolation, physico-chemical properties and biological activities. | novel antibiotics named kigamicin a, b, c, d, and e were discovered from the culture broth of amycolatopsis sp. ml630-mf1 by their selective killing activity against panc-1 cells only under a nutrient starved condition. under a condition of nutrient starvation, kigamicins a, b, c, and d inhibited panc-1 cell survival at 100 times lower concentration than in normal culture. kigamicins showed antimicrobial activity against gram-positive bacteria including methicillin resistant staphylococcus aureu ... | 2003 | 15015727 |
| cloning and characterization of the ferulic acid catabolic genes of sphingomonas paucimobilis syk-6. | sphingomonas paucimobilis syk-6 degrades ferulic acid to vanillin, and it is further metabolized through the protocatechuate 4,5-cleavage pathway. we obtained a tn5 mutant of syk-6, fa2, which was able to grow on vanillic acid but not on ferulic acid. a cosmid which complemented the growth deficiency of fa2 on ferulic acid was isolated. the 5.2-kb bamhi-ecori fragment in this cosmid conferred the transformation activity of ferulic acid to vanillin on escherichia coli host cells. a sequencing ana ... | 2002 | 12200295 |
| antimicrobial resistance gene delivery in animal feeds. | avoparcin, a glycopeptide antimicrobial agent related to vancomycin, has been used extensively as a growth promoter in animal feeds for more than 2 decades, and evidence has shown that such use contributed to the development of vancomycin-resistant enterococci. a cluster that includes three genes, vanh, vana, and vanx, is required for high-level resistance to glycopeptides. in the vancomycin producer amycolatopsis orientalis c329.2, homologs of these genes are present, suggesting an origin for t ... | 2004 | 15200859 |
| screening, overexpression and characterization of an n-acylamino acid racemase from amycolatopsis orientalis subsp. lurida. | thirty-one different actinomycete strains were used in a genetic screening using pcr and southern hybridization methods to detect n-acetylamino acid racemases (aar) in order to obtain enzymes with different properties. cloning and sequencing of a 2.5 kb ecori dna fragment from amycolatopsis orientalis subsp. lurida revealed the coding gene of an n-acetylamino acid racemase, which had identities to the aar gene of amycolatopsis sp. ts-1-60 [tokuyama and hatano (1995) appl microbiol biotechnol 42: ... | 2001 | 11341319 |
| three new antibiotic producing species of the genus amycolatopsis, amycolatopsis balhimycina sp. nov., a. tolypomycina sp. nov., a. vancoresmycina sp. nov., and description of amycolatopsis keratiniphila subsp. keratiniphila subsp. nov. and a. keratiniphila subsp. nogabecina subsp. nov. | screening of indian soils for strains producing antibiotics active against methicillin resistant staphylococci resulted in the isolation of the actinomycetes fh 1894t, st 101170t, and fh 1893t, producing novel glycopeptide antibiotics and a polyenic compound, respectively. studies of the cellular fatty acids and the absence of mycolic acids as well as the 16s rrna gene sequence analysis of the producers indicated their membership to the genus amycolatopsis. comparison of genomic and metabolic pr ... | 2003 | 12747408 |
| amycolatopsis keratiniphila sp. nov., a novel keratinolytic soil actinomycete from kuwait. | a keratinolytic, nocardioform actinomycete, strain d2(t), was isolated from kuwait marsh soil by the bait technique using animal wool. strain d2(t) was an aerobic, gram-positive organism that produced light-grey aerial mycelium but no specific spore chains. 16s rdna sequence analyses and chemotaxonomic markers were consistent with the classification of strain d2(t) in the genus amycolatopsis, i.e. it had meso-diaminopimelic acid in its peptidoglycan, arabinose and galactose as its diagnostic sug ... | 2003 | 12807215 |
| nicotinoprotein (nad+ -containing) alcohol dehydrogenase: structural relationships and functional interpretations. | the primary structure of nicotinoprotein alcohol dehydrogenase (adh) from amycolatopsis methanolica was determined and used for modelling against known adh structures, and for evaluation of the coenzyme binding. the results establish the medium-chain dehydrogenase/reductase nature of the nicotinoprotein adh. its subunit model and that of the human class ibeta adh subunit structure are similar, with mean a carbon deviations of 0.95 a, but they differ in seven loops. nicotinoprotein adh occupies a ... | 2003 | 12827287 |
| crystal structure of oxyc, a cytochrome p450 implicated in an oxidative c-c coupling reaction during vancomycin biosynthesis. | gene inactivation studies point to the involvement of oxyc in catalyzing the last oxidative phenol coupling reaction during glycopeptide antibiotic biosynthesis. presently, the substrate and exact timing of the oxyc reaction are unknown. the substrate might be the bicyclic heptapeptide or a thioester derivative bound to a protein carrier domain. oxyc from the vancomycin producer amycolatopsis orientalis was produced in escherichia coli and crystallized, and its structure was determined to 1.9 a ... | 2003 | 12888556 |
| mutasynthesis of glycopeptide antibiotics: variations of vancomycin's ab-ring amino acid 3,5-dihydroxyphenylglycine. | in the mutasynthetic approach, the deltadpga mutant of the vancomycin-type glycopeptide antibiotic producer amycolatopsis balhimycina, which is deficient in the synthesis of 3,5-dihydroxyphenylglycine (dpg), was supplemented with synthetic dpg analogues to obtain the corresponding modified glycopeptides. sterically more demanding 3,5-disubstituted methoxy derivatives as well as monosubstituted dpg analogues were accepted as substrates. these facts indicate that steric and electronic requirements ... | 2004 | 15137740 |
| exploration of amycolatopsis diversity in soil using genus-specific primers and novel selective media. | large numbers of actinomycetes provisionally assigned to the genus amycolatopsis were isolated from soil samples using a dilution plate procedure and three novel media designed to be selective for members of this genus. a set of genus-specific oligonucleotide primers developed for the rapid identification of unknown amycolatopsis strains was used to determine whether representative strains taken from the selective isolation plates produced the diagnostic amplification product. the 175 isolates w ... | 2006 | 16466884 |
| heterologous expression of glycopeptide resistance vanhax gene clusters from soil bacteria in enterococcus faecalis. | the aim of the study was to determine whether glycopeptide resistance gene clusters from soil bacteria could be heterologously expressed in enterococcus faecalis and adapt to the new host following exposure to vancomycin. | 2006 | 16476725 |
| improvement of rifemycins production by amycolatopsis mediterranei in batch and fed-batch cultures. | the production of rifamycins b and sv using glucose as main c-source by amycolatopsis mediterranei in batch and fed-batch culture was investigated. fed-batch culture using glucose as mono feeding substrate either in the form of pulse addition, in case of shake flask, or with constant feeding rate, in bioreactor level, proved to be an alternative production system with a significant increase in both volumetric and specific antibiotic production. the maximal concentrations of about 1146 mg/l and 2 ... | 2003 | 14743983 |
| biodegradation of poly(l-lactide). | the biodegradation of poly(l-lactide) (pla) is reviewed. the important role of actinomycetes in pla degradation is emphasized. these pla-degrading actinomycetes belong phylogenetically to the pseudonocardiaceae family and related genera, including amycolatopsis, lentzea, streptoalloteichus, kibdelosporangium and saccharothrix. a pla-degrading enzyme purified from an isolated amycolatopsis strain-41 has substrate specificity on pla higher than proteinase k. the application of these strains and th ... | 2004 | 15274245 |
| characterization of a truncated lipoarabinomannan from the actinomycete turicella otitidis. | lipoarabinomannan (lam) lipoglycans have been characterized from a range of mycolic acid-containing actinomycetes and from the amycolate actinomycete amycolatopsis sulphurea. to further understand the structural diversity of this family, we have characterized the lipoglycan of the otic commensal turicella otitidis. t. otitidis lam (totlam) has been determined to consist of a mannosyl phosphatidylinositol anchor unit carrying an (alpha 1-->6)-linked mannan core and substituted with terminal-arabi ... | 2005 | 15659663 |
| a homologue of the mycobacterium tuberculosis papa5 protein, rif-orf20, is an acetyltransferase involved in the biosynthesis of antitubercular drug rifamycin b by amycolatopsis mediterranei s699. | | 2005 | 15791687 |
| influence of nutritional supplements on keratinolysis by amycolatopsis keratinophila. | keratinolytic potential of a. keratinophila (dsm 44409t), a newly described amycolatopsis sp. isolated from cultivated soil in kuwait, was demonstrated using keratinazure as the sole source of carbon and nitrogen as estimated by gel diffusion assay. effects of 12 various nutritional supplements on the keratinolytic and azocollytic activities were determined. nh4h2po4 and kno3 in the medium supported a significantly higher keratinolytic activity than other supplements. however, azocollytic activi ... | 2003 | 15248487 |
| comparative analysis and insights into the evolution of gene clusters for glycopeptide antibiotic biosynthesis. | the bal, cep, dbv, sta and tcp gene clusters specify the biosynthesis of the glycopeptide antibiotics balhimycin, chloroeremomycin, a40926, a47934 and teicoplanin, respectively. these structurally related compounds share a similar mechanism of action in their inhibition of bacterial cell wall formation. comparative sequence analysis was performed on the five gene clusters. extensive conserved synteny was observed between the bal and cep clusters, which direct the synthesis of very similar compou ... | 2005 | 16007453 |
| biotransformation of bile acids by pathogenic actinomycetes nocardia otitidiscaviarum and amycolatopsis sp. strains. | three sterol-type compounds (compounds 4, 5 and 6) were isolated from culture broth of pathogenic nocardia otitidiscaviarum ifm 0988 and amycolatopsis sp. ifm 0703 strains which were isolated from japanese patients. the structures of the compounds were determined by nmr and mass spectrometric analyses. the structural studies indicated that compound 4 is a biotransformation product from cholic acid derivative in a nutrient culture medium constituent by a reductase-type enzyme, and the remaining t ... | 2005 | 16060390 |
| identification of tailoring genes involved in the modification of the polyketide backbone of rifamycin b by amycolatopsis mediterranei s699. | rifamycin b biosynthesis by amycolatopsis mediterranei s699 involves a number of unusual modification reactions in the formation of the unique polyketide backbone and decoration of the molecule. a number of genes believed to be involved in the tailoring of rifamycin b were investigated and the results confirmed that the formation of the naphthalene ring moiety of rifamycin takes place during the polyketide chain extension and is catalysed by rif-orf19, a 3-(3-hydroxyphenyl)propionate hydroxylase ... | 2005 | 16079331 |
| cloning and preliminary characterization of lh3 gene encoding a putative acetyltransferase from a rifamycin sv-producing strain amycolatopsis mediterranei. | an orf located immediately downstream of glnr gene was cloned from amycolatopsis mediterranei u32 and was named lh3. sequence analysis revealed that lh3 encodes a putative acetyltransferase, which shows high amino acid sequence similarities to the mycothiol synthase (mshd) from other actinomycetes. for functional analysis, mutation in lh3 gene was generated by gene replacement with an apramycin resistance gene through homologous recombination. compared with the wild type strain, the resulting mu ... | 2005 | 16132864 |
| purification and characterization of a chitinase from amycolatopsis orientalis with n-acetyllactosamine-repeating unit releasing activity. | we report a novel enzyme from the culture filtrate of amycolatopsis orientalis, that endoglycosidically releases an n-acetyllactosamine-repeating unit (galbeta1,4glcnacbeta1,3galbeta1,4glcnac, ln2) from a synthetic chromogenic substrate galbeta1,4glcnacbeta1,3galbeta1,4glcnacbeta-pnp (1). the enzyme activity was purified by 80% saturated ammonium sulfate precipitation followed by gel filtration and affinity chromatography. the enzyme splits 1, galbeta1,4glcnacbeta-pnp (2), glcnacbeta1,3galbeta1, ... | 2005 | 16143301 |
| amycolatopsis plumensis sp. nov., a novel bioactive actinomycete isolated from a new-caledonian brown hypermagnesian ultramafic soil. | the taxonomic position of an actinomycete isolated from a brown hypermagnesian ultramafic soil was examined using a polyphasic approach. the organism, which was designated sbhs strp1(t), was found to have chemical and morphological properties typical of amycolatopsis strains. it was most closely associated with amycolatopsis kentuckyensis, amycolatopsis lexingtonensis, amycolatopsis rifamycinica, amycolatopsis pretoriensis and amycolatopsis tolypomycina on the basis of 16s rrna gene sequence dat ... | 2005 | 16166709 |
| biochemical mechanism of the effect of barbital on rifamycin b biosynthesis by amycolatopsis mediterranei (m18 strain). | it is well known that 5,5-diethylbarbituric acid (barbital) in the culture medium can stimulate the production of rifamycin b by amycolatopsis mediterranei, particularly in industrial processes. however, the mechanism by which barbital exerts this effect is unknown. results in this work show that the barbital effect is only evident under low aeration conditions (50-ml microfermentors with 7 ml of medium, 0.08 l/h air flow). under these conditions, cultures with barbital showed similar co2 produc ... | 2003 | 16233407 |
| cloning and characterization of the chromosomal replication origin region of amycolatopsis mediterranei u32. | the chromosomal replication origins (oric) of gram positive, acid-fast actinomycetes have been investigated in streptomycetes and mycobacteria. a 1339 bp dna fragment of the putative oric region from the rifamycin sv producer amycolatopsis mediterranei u32 was cloned by pcr amplification employing primers designed based on the conserved flanking genes of dnaa and dnan. the 884 bp sequence of the intergenic region between dnaa and dnan genes consists of 19 dnaa-boxes and two 13-mer at-rich sequen ... | 2005 | 15936727 |
| [cloning, expression and transcriptional analysis of biotin carboxyl carrier protein gene (acca) from amycolatopsis mediterranei u32 ]. | acetyl coa carboxylase (ec 6.4.1.2, acc) catalyzes the atp-dependent carboxylation of acetyl coa to yield malonyl coa, which is the first committed step in fatty acid synthesis. a pair of degenerate pcr primers were designed according to the conserved amino acid sequence of acca from m. tuberculosis and s. coelicolor. the product of the pcr amplification, a dna fragment of 250bp was used as a probe for screening the u32 genomic cosmid library and its gene, acca, coding the biotinylated protein s ... | 2003 | 16276872 |
| [characterization of amycolatopsis meditteranei u32 chromosome by pulse-field gel electrophoresis]. | amycolatopsis meditteranei u32 is an industrial strain with high yield of rifamycin sv. its chromosome structure was characterized by pulse-field gel electrophoresis. the topological structure of u32 chromosome was linear and its genome size was about 10 mb. there was no internal plasmid found. gene encoding several enzymes involved in rifamycin bio-synthesis and relevant primary metabolism as well as protein related to metabolic regulation were localized by southern blot. the results revealed t ... | 2003 | 16276900 |
| structured kinetic model to represent the utilization of multiple substrates in complex media during rifamycin b fermentation. | industrial fermentations typically use media that are balanced with multiple substitutable substrates including complex carbon and nitrogen source. yet, much of the modeling effort to date has mainly focused on defined media. here, we present a structured model that accounts for growth and product formation kinetics of rifamycin b fermentation in a multi-substrate complex medium. the phenomenological model considers the organism to be an optimal strategist with an in-built mechanism that regulat ... | 2006 | 16302259 |