| thiazocins, new aldose reductase inhibitors from actinosynnema sp. 1. fermentation, isolation and characterization. | new antibiotics designated as thiazocins a and b were isolated from the culture broth of actinosynnema sp. c-304. thiazocins a and b exhibited inhibitory activities against an aldose reductase from human placenta. | 1991 | 1908854 |
| actinosynnema mirum, a new producer of nocardicin antibiotics. | | 1983 | 6833153 |
| lentzea gen. nov., a new genus of the order actinomycetales. | we describe a new genus of mesophilic actinomycetes, for which we propose the name lentzea. the strains of this genus form abundant aerial hyphae that fragment into rod-shaped elements. whole-cell hydrolysates contain the meso isomer of diaminopimelic acid and no characteristic sugar (wall chemotype iii). the phospholipid pattern type is type pii (phosphatidylethanolamine is the characteristic phospholipid); the major menaquinone is mk-9. the fatty acid profile comprises saturated, unsaturated, ... | 1995 | 7537071 |
| isolation of propioxatin a from actinosynnema sp. si-23 during a screening for serratia piscatorum metalloproteinase inhibitors. | an inhibitor of serratia metalloproteinase was found in the cultured broth of strain si-23, which was identified to be actinosynnema sp. the inhibitor had a potent inhibitory effect on serratia metalloproteinase and a weak effect on thermolysin, but no effect on other groups of proteinases. the structure of the inhibitor was deduced to be propioxatin a, reported as an enkephalinase b inhibitor. | 1997 | 9095561 |
| phylogenetic analysis of saccharothrix and related taxa: proposal for actinosynnemataceae fam. nov. | partial sequences for 16s rdna were determined for strains of the genus saccharothrix, including most described species, as well as strains of the described species of the related genera kutzneria, actinokineospora and actinosynnema. these were aligned with published sequences for other species of these genera, as well as those of the genera 'actinoalloteichus', 'asiosporangium', lentzea, kutzneria, streptoalloteichus and representative taxa from other actinomycete families. phylogenetic analysi ... | 2000 | 10826820 |
| application of a method incorporating differential centrifugation for selective isolation of motile actinomycetes in soil and plant litter. | the present paper describes a simple enrichment technique which enables rapid and selective isolation of diverse zoosporic actinomycete genera directly from soil and plant litter. this technique, designated the rehydration and centrifugation (rc) method, consists of immersing the air-dried source material in 10 mm phosphate buffer containing 10% soil extract, letting the preparation stand at 30 degrees c for 90 min, followed by centrifugation of the fluid at 1,500 x g for 20 min. portions of the ... | 2000 | 11204769 |
| functional expression of genes involved in the biosynthesis of the novel polyketide chain extension unit, methoxymalonyl-acyl carrier protein, and engineered biosynthesis of 2-desmethyl-2-methoxy-6-deoxyerythronolide b. | a subcluster of five genes, asm13-17, from the ansamitocin biosynthetic gene cluster of actinosynnema pretiosum was coexpressed in streptomyces lividans with the genes encoding the 6-deoxyerythronolide b (6-deb) synthase from saccharopolyspora erythraea, in which the methylmalonate-specifying at6 domain had been replaced by the methoxymalonate-specifying at8 domain from the fk520 cluster of streptomyces hygroscopicus. the engineered strain produced the predicted product, 2-desmethyl-2-methoxy-de ... | 2002 | 11996558 |
| identification of asm19 as an acyltransferase attaching the biologically essential ester side chain of ansamitocins using n-desmethyl-4,5-desepoxymaytansinol, not maytansinol, as its substrate. | the potent antitumor activity of the ansamitocins, polyketides isolated from actinosynnema pretiosum, is absolutely dependent on a short acyl group esterified to the c-3 oxygen of the macrolactam ring. asm19, a gene in the ansamitocin biosynthetic gene cluster with homology to macrolide o-acyltransferase genes, is thought to encode the enzyme catalyzing this esterification. a mutant carrying an inactivated asm19 no longer produced ansamitocins but accumulated n-desmethyl-4,5-desepoxymaytansinol, ... | 2002 | 12047169 |
| the biosynthetic gene cluster of the maytansinoid antitumor agent ansamitocin from actinosynnema pretiosum. | maytansinoids are potent antitumor agents found in plants and microorganisms. to elucidate their biosynthesis at the biochemical and genetic level and to set the stage for their structure modification through genetic engineering, we have cloned two gene clusters required for the biosynthesis of the maytansinoid, ansamitocin, from a cosmid library of actinosynnema pretiosum ssp. auranticum atcc 31565. this is a rare case in which the genes involved in the formation of a secondary metabolite are d ... | 2002 | 12060743 |
| [microbial succession on lignite along with weathering]. | six different weathered lignite samples were examined by scanning electron microscopy. few microorganisms were observed on lignit just excavated and only spores and short hyphae were observed on lignite samples excavated 5 months, 1 year and 4 years before sampling. when lignite samples were moistened with distilled water and incubated for 10 days, actinomycetes proliferated significantly on lignite samples that were just excavated or excavated 5 months before sampling. the growth of bacteria wa ... | 1998 | 12548918 |
| [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 |
| 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 |
| the post-polyketide synthase modification steps in the biosynthesis of the antitumor agent ansamitocin by actinosynnema pretiosum. | the functions of six genes in the ansamitocin biosynthetic gene cluster of actinosynnema pretiosum have been investigated by gene inactivation and chemical analysis of the mutants. they encode a halogenase (asm12), a carbamoyltransferase (asm21), a 20-o-methyltransferase (asm7), a 3-o-acyltransferase (asm19), an epoxidase (asm11), and an n-methyltransferase (asm10), respectively, and are responsible for the six post-pks modification steps in ansamitocin formation. several of the enzymes have rel ... | 2003 | 14624546 |
| recent developments in the maytansinoid antitumor agents. | maytansine and its congeners have been isolated from higher plants, mosses and from an actinomycete, actinosynnema pretiosum. many of these compounds are antitumor agents of extraordinary potency, yet phase ii clinical trials with maytansine proved disappointing. the chemistry and biology of maytansinoids has been reviewed repeatedly in the late 1970s and early 1980s; the present review covers new developments in this field during the last two decades. these include the use of maytansinoids as " ... | 2004 | 14709862 |
| a novel amide n-glycoside of ansamitocins from actinosynnema pretiosum. | | 2004 | 15303496 |
| determination of the cryptic stereochemistry of the first pks chain-extension step in ansamitocin biosynthesis by actinosynnema pretiosum. | the biosynthesis of the antitumor antibiotic, ansamitocin, involves the assembly of a linear octaketide on the ansamitocin (asm) polyketide synthase (pks), which is then cyclized to proansamitocin and further modified to the final product. in the first chain-extension step on the asm pks, a stereocenter is generated which is then obliterated in a subsequent double-bond migration. the cryptic configuration at this stereocenter was determined by first synthesizing the two enantiomers of the interm ... | 2006 | 16927319 |
| [activity and ecological distribution of actinomycetes from soil in the southeastern of tibet]. | the soil samples were collected from primeval forest, alpine meadow, marshy, grainfield and vegetable farmland ect. 9 different kinds of vegetative type and from 2970 - 4590 altitude of southeastern of tibet. the amount,composition, antimicrobial activity of mesophilic and psychrophilic actinomycetes and some mesophilic actinomycetes of physiological and biochemical characteristics were studied by normal methods. these actinomycetes were identified at genus level by their morphological propertie ... | 2006 | 17172027 |
| chemoenzymatic approaches toward dechloroansamitocin p-3. | [reaction: see text] the enantioselective total synthesis of proansamitocin, a key biosynthetic intermediate of the highly potent antitumor agent ansamitocin p-3, is described which bears a diene-ene rcm as the key macrocyclization step. feeding of proansamitocin to an ahba block mutant actinosynnema pretiosum (hgf073) yielded ansamitocin p-3 as well as dechloroansamitocin p-3, the latter also being formed upon fermentation in the presence of 3-amino-5-methoxybenzoic acid. | 2007 | 17378571 |
| new amide n-glycosides of ansamitocins identified from actinosynnema pretiosum. | by using preparative tlc as the critical isolation procedure, two compounds, including one new amide n-glycosides of ansamitocin (2), were isolated from actinosynnema pretiosum. the compounds were elucidated as n-demethyl-n-beta-d-glucopyranosyl ansamitocin p-2, named ansamitocinoside p-2 (1), and n-demethyl-n-beta-d-glucopyranosyl ansamitocin p-1, named ansamitocinoside p-1 (2) on the basis of their spectral data. the 1h-nmr and 13c-nmr assignments were made for 1 and 2 while the 13c-nmr assign ... | 2007 | 17679541 |
| an integrative expression vector for actinosynnema pretiosum. | the actinomycete actinosynnema pretiosum ssp. auranticum has commercial importance due to its production of ansamitocin p-3 (ap-3), a potent antitumor agent. one way to increase ap-3 production would be to constitutively express selected genes so as to relieve bottlenecks in the biosynthetic pathway; however, an integrative expression vector for a. pretiosum is lacking. the aim of this study was to construct a vector for heterologous gene expression in a. pretiosum. | 2007 | 17956638 |
| amide n-glycosylation by asm25, an n-glycosyltransferase of ansamitocins. | ansamitocins are potent antitumor maytansinoids produced by actinosynnema pretiosum. their biosynthesis involves the initial assembly of a macrolactam polyketide, followed by a series of postpolyketide synthase (pks) modifications. three ansamitocin glycosides were isolated from a. pretiosum and fully characterized structurally as novel ansamitocin derivatives, carrying a beta-d-glucosyl group attached to the macrolactam amide nitrogen in place of the n-methyl group. by gene inactivation and com ... | 2008 | 18721757 |
| timing of the delta(10,12)-delta(11,13) double bond migration during ansamitocin biosynthesis in actinosynnema pretiosum. | the timing of introduction of the unusually placed delta(11,13) diene system in ansamitocin (ap) biosynthesis was probed by synthesizing optically active potential tri- and tetraketide intermediates as their snac thioesters. an ap-nonproducing mutant actinosynnema pretiosum was complemented by the r enantiomer of the triketide and by the tetraketide with rearranged double bonds, but not by the tetraketide carrying the double bonds in conjugation to the thioester function. the results show that t ... | 2009 | 19292483 |
| constitutive overexpression of asm2 and asm39 increases ap-3 production in the actinomycete actinosynnema pretiosum. | constitutive overexpression of regulators in the ansamitocin biosynthetic cluster of actinosynnema pretiosum was investigated as a strategy to increase the production of ansamitocin-p3 (ap-3), a clinically promising chemotherapeutic agent. putative transcriptional regulators asm2, asm29, and asm34 as well as the putative regulatory protein asm39 were cloned into a single-site integrative vector and a multicopy replicative vector, pap40 and prep, respectively, and then transformed into a. pretios ... | 2009 | 19609582 |
| preparative isolation and purification of anti-tumor agent ansamitocin p-3 from fermentation broth of actinosynnema pretiosum using high-performance counter-current chromatography. | ansamitocin p-3 is a potent anti-tumor maytansinoid found in actinosynnema pretiosum. however, due to the complexity of the fermentation broth of actinomycete, how to effectively separate ansamitocin p-3 is still a challenge. in this study, both analytical and preparative high-performance counter-current chromatography were successfully used to separate and purify ansamitocin p-3 from fermentation broth. a total of 28.8 mg ansamitocin p-3 with purity of 98.4% was separated from 160 mg crude samp ... | 2010 | 20235129 |
| a new antitumour ansamitocin from actinosynnema pretiosum. | a new compound of ansamitocin was isolated from the extracts of fermentation medium of mutant strain hgf052 derived from actinosynnema pretiosum ssp. aurantium atcc 31565, and identified as n-demethyl-desepoxy-9-methoxy-maytansinol (1) on the basis of extensive spectroscopic methods. bioassay results showed that compound 1 had cytotoxic activity against hl-60 and bel-7402 cell lines. | 2010 | 20582809 |
| antibiotic producing potentials of three freshwater actinomycetes isolated from the eastern cape province of south africa. | crude extracts of three actinomycetes species belonging to saccharopolyspora (tr 046 and tr 039) and actinosynnema (tr 024) genera were screened for antibacterial activities against a panel of several bacterial strains. the extracts showed antibacterial activities against both gram-negative and gram-positive test bacteria with inhibition zones ranging from 8 to 28 mm (tr 046); 8 to15 mm (tr 039); and 10 to 13 mm (tr 024). the minimum inhibitory concentrations ranged from 0.078 to 10 mg/ml (tr 04 ... | 2010 | 20717525 |
| enhanced production of ansamitocin p-3 by addition of isobutanol in fermentation of actinosynnema pretiosum. | supply of isobutanol to enhance the production of anti-tumor agent ansamitocin p-3 (ap-3) in medium containing agro-industrial residues was investigated with analysis of gene transcription, enzyme activity, and intermediate accumulation. under the optimal addition of isobutanol, about 4-fold improvement of ap-3 production was obtained, and the consumption of isobutanol and accumulation of isobutyrate, malonyl-coa, and acetyl-coa were observed. compared to the control without isobutanol addition, ... | 2010 | 20980145 |
| cyclization of synthetic seco-proansamitocins to ansamitocin macrolactams by actinosynnema pretiosum as biocatalyst. | | 2010 | 21077088 |
| characterization of the tunicamycin gene cluster unveiling unique steps involved in its biosynthesis. | tunicamycin, a potent reversible translocase i inhibitor, is produced by several actinomycetes species. the tunicamycin structure is highly unusual, and contains an 11-carbon dialdose sugar and an α, β-1″,11'-glycosidic linkage. here we report the identification of a gene cluster essential for tunicamycin biosynthesis by high-throughput heterologous expression (hhe) strategy combined with a bioassay. introduction of the genes into heterologous non-producing streptomyces hosts results in producti ... | 2010 | 21153459 |
| complete genome sequence of actinosynnema mirum type strain (101). | actinosynnema mirum hasegawa et al. 1978 is the type species of the genus, and is of phylogenetic interest because of its central phylogenetic location in the actino-synnemataceae, a rapidly growing family within the actinobacterial suborder pseudo-nocardineae. a. mirum is characterized by its motile spores borne on synnemata and as a producer of nocardicin antibiotics. it is capable of growing aerobically and under a moderate co(2) atmosphere. the strain is a gram-positive, aerial and substrate ... | 2009 | 21304636 |
| n-methylation of the amide bond by methyltransferase asm10 in ansamitocin biosynthesis. | ansamitocins are potent antitumor agents produced by actinosynnema pretiosum. as deduced from their structures, an n-methylation on the amide bond is required among the various modifications. the protein encoded by asm10 belongs to the sam-dependent methyltransferase family. through gene inactivation and complementation, asm10 was proved to be responsible for the n-methylation of ansamitocins. asm10 is a 33.0 kda monomer, as determined by gel filtration. by using n-desmethyl-ansamitocin p-3 as s ... | 2011 | 21681880 |
| Enhanced production of ansamitocin P-3 by addition of Mg2+ in fermentation of Actinosynnema pretiosum. | The effect of divalent metal ions (i.e., Mn(2+), Mg(2+), Zn(2+), Cu(2+), and Co(2+)) on the production of anticancer ansamitocin P-3 (AP-3) by submerged cultures of Actinosynnema pretiosum in medium containing agro-industrial residues was investigated, and Mg(2+) was found to be the most effective. Under the optimal condition of Mg(2+) addition, the maximal AP-3 production titer reached 85 mg/L, which was 3.0-fold that of the control. The activities of methylmalonyl-CoA carboxyltransferase (MCT) ... | 2011 | 21907573 |
| Dual carbamoylations on the polyketide and glycosyl moiety by asm21 result in extended ansamitocin biosynthesis. | Carbamoylation is one of the post-PKS modifications in ansamitocin biosynthesis. A novel ansamitocinoside with carbamoyl substitution at the C-4 hydroxyl group of the N-ß-D-glucosyl moiety was identified from the ansamitocin producer, Actinosynnema pretiosum. Through biotransformation, the carbamoyltransferase gene asm21 was suggested to be responsible for the carbamoylation of the glucosyl moiety. Three new derivatives without the backbone carbamoyl group were isolated from an asm21 mutant and ... | 2011 | 22195559 |
| Broad substrate specificity of the amide synthase in S. hygroscopicus - new 20-membered macrolactones derived from geldanamycin. | The amide synthase of the geldanamycin producer, Streptomyces hygroscopicus, shows a broader chemoselectivity than the corresponding amide synthase present in Actinnosynnema pretiosum, the producer of the highly cytotoxic ansamycin antibiotics, the ansamitocins. This was demonstrated when blocked mutants of both strains incapable of biosynthesizing 3-amino-5-hydroxybenzoic acid (AHBA), the polyketide synthase starter unit of both natural products, were supplemented with 3-amino-5-hydroxymethylbe ... | 2011 | 22136518 |
| mutational biosynthesis of ansamitocin antibiotics: a diversity-oriented approach to exploit biosynthetic flexibility. | new ansamitocin derivatives were prepared by feeding aminobenzoic acid derivatives to cultures of actinosynnema pretiosum hgf073, a mutant strain blocked in the biosynthesis of the required 3-amino-5-hydroxybenzoic acid (ahba) starter unit. use of several aminobenzoic acids as precursors led to a spectrum of products, reflecting the sequence of post-pks tailoring steps involved in the generation of ansamitocins and adding novel aspects to the published suggestion model of post-pks tailoring logi ... | 2011 | 22238146 |