| state and reactivity of tryptophyl residues in two bacterial proteases from sorangium sp. | the state and reactivity of tryptophyl residues in two proteolytic enzymes from sorangium sp. were investigated by means of the following methods: spectrophotometric oxidation of tryptophans with n-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide, and h2o2 in dioxane, optical rotatory dispersion, ultraviolet difference spectrophotometry, solvent perturbation and viscosity measurements. out of two tryptophyl residues/molecule of alpha-lytic protease, one appears to be completely buried, while th ... | 1975 | 238618 |
| characterization of trypsin and elastase from the moose (alces alces). i. amino acid composition and specificity towards polypeptides. | trypsin and elastase isolated from the pancreas of the moose (alces alces), a member of the cervidae (deer) family, were characterized with respect to their amino acid composition and specificity towards polypeptides. moose trypsin possessed 234 residues, based on alanine recoveries equal to 16.0 residues, with a molecular weight calculated at 24 476. moose trypsin readily hydrolysed peptide bonds in which the carbonyl group was contributed by arginine, lysine and s-2-aminoethylcysteine as indic ... | 1975 | 1125277 |
| sensitivity of some human pathogenic yeasts and systemic fungi to myxin. | myxin, a relatively new antibacterial and antifungal antibiotic, produced by a species of sorangium, was used to investigate its effectiveness against some yeasts and dimorphic fungi associated with human diseases. results indicated that the minimal fungicidal concentrations (mfc) of myxin for candida albicans, c. krusei, c. parapsilosis, c. tropicalis, and torulopsis glabrata were 0.39-6.25 mug/ml, and for c. guilliermondii and c. tropicalis 12.5-25 mug/ml. the mfc for blastomyces dermatitidis ... | 1975 | 1171116 |
| ambruticin s production in air-lift and stirred-tank bioreactors. | using the method of equi-inocular synchronized comparative fermentation (eiscf) the cultivation of sorangium cellulosum so ce 10 and production of the polyketide antibiotic ambruticin s was compared in stirred-tank and air-lift reactors of different geometry. this method requires that inocula originate from the same pre-culture and cultivation parameters are synchronized to similar values. similar ambruticin yields were obtained from both reactor systems provided that the concentration of dissol ... | 1990 | 1367518 |
| ambruticin s production in amino acid rich media. | the antimycoticum ambruticin was produced by cultivating the myxobacterium sorangium cellulosum in shake flasks and stirred tank reactors with 10- and 30-l working volumes. during growth and product formation amino acid concentrations in the complex media were measured by hplc. in the logarithmic growth phase free aspartate and glutamate were assimilated without product formation. after consumption of aspartate and glutamate, growth was limited and ambruticin production set in. the effects of bi ... | 1990 | 1369434 |
| transfer of mobilizable plasmids to sorangium cellulosum and evidence for their integration into the chromosome. | recombinant vectors derived from the broad-host-range mobilizable plasmid psup2021 were constructed and transferred by incp-mediated conjugation from escherichia coli to sorangium cellulosum, where they were integrated into the chromosome by homologous recombination and maintained stably. this appears to be the first system of gene transfer to s. cellulosum. | 1992 | 1409972 |
| 5s rrna sequences of myxobacteria and radioresistant bacteria and implications for eubacterial evolution. | 5s rrna sequences were determined for the myxobacteria cystobacter fuscus, myxococcus coralloides, sorangium cellulosum, and nannocystis exedens and for the radioresistant bacteria deinococcus radiodurans and deinococcus radiophilus. a dendrogram was constructed by using weighted pairwise grouping based on these and all other previously known eubacterial 5s rrna sequences, and this dendrogram showed differences as well as similarities compared with results derived from 16s rrna analyses. in the ... | 1990 | 2125831 |
| the sorangicins, novel and powerful inhibitors of eubacterial rna polymerase isolated from myxobacteria. | a new antibiotic, sorangicin, was isolated from the culture supernatant of the myxobacterium, sorangium (polyangium) cellulosum strain so cel2. it is a macrocyclic lactone carbonic acid and is produced in two structural variants, sorangicins a and b. in addition small quantities of the respective glycosides, sorangiosids a and b, may be found. the antibiotic acts mainly against gram-positive bacteria, including myocobacteria, with mic values between 0.01 and 0.1 microgram/ml, but at higher conce ... | 1987 | 3104268 |
| [the study of enzymatic cellulolysis of sorangium composition]. | | 1968 | 4880382 |
| distribution of sorangium cellulosum. | the myxobacterium sorangium cellulosum exists and plays an important role in soil ecology by its ability to degrade cellulosic materials; it was found to be widely distributed in north american soils. | 1971 | 4943594 |
| carotenoid pigments of sorangium compositum (myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides. | | 1971 | 5099150 |
| lytic enzymes of sorangium sp. isolation and enzymatic properties of the alpha- and beta-lytic proteases. | | 1965 | 5326246 |
| simplified procedures for production and isolation of the bacteriolytic proteases of sorangium sp. | | 1967 | 5340601 |
| a comparison of properties of the alpha-lytic protease of sorangium sp. and porcine elastase. | | 1970 | 5465371 |
| kinetic properties of the alpha-lytic protease of sorangium sp., a bacterial homologue of the pancreatopeptidases. | | 1969 | 5778213 |
| some features of the optical rotatory dispersion spectrum of the alpha-lytic protease of sorangium sp. | | 1969 | 5778214 |
| morphology and morphogenesis of sorangium compositum. | | 1969 | 5791933 |
| lytic enzymes of sorangium sp. some aspects of enzyme production in submerged culture. | | 1965 | 5880180 |
| lytic enzymes of sorangium sp. a comparison of some physical properties of the alpha- and beta-lytic proteases. | | 1965 | 5880181 |
| lytic enzymes of sorangium sp. a comparison of the proteolytic properties of the alpha- and beta-lytic proteases. | | 1965 | 5880182 |
| lytic enzymes of sorangium sp. action of the alpha- and beta-lytic proteases on two bacterial mucopeptides. | | 1965 | 5880183 |
| a wide-spectrum antibiotic produced by a species of sorangium. | | 1966 | 5929152 |
| the nature of the bacteriolytic proteases of sorangium sp. | | 1966 | 6007446 |
| concerning the nature of the alpha- and beta-lytic proteases of sorangium sp. | | 1967 | 6034704 |
| amino acid and metal composition of the alpha- and beta-lytic proteases of sorangium sp. | | 1967 | 6034705 |
| the cause of the bi-component electrophoretic pattern of sorangium beta-lytic protease in acetate buffer containing 7 m urea. | | 1967 | 6039658 |
| amino acid sequence around the histidine residue of the alpha-lytic protease of sorangium sp., a bacterial homolog of the pancreatic serine proteases. | | 1967 | 6042772 |
| kinetic properties of the alpha-lytic protease of sorangium sp. | | 1967 | 6042773 |
| the fine structure of chondrococcus columnaris. ii. structure and formation of rhapidosomes. | when cells of c. columnaris were broken open, treated with pta, and examined in the electron microscope, tubular structures (rhapidosomes) were present in the preparations. the rhapidosomes are approximately 300 a in diameter. their length varies from about 500 to about 15,000 a. an axial hole which runs the length of the rhapidosomes appears to widen and narrow with a regular periodicity. end-on views of short segments of rhapidosomes revealed the presence of subunits around their outside perip ... | 1967 | 6061714 |
| protease production by fermentation of fish solubles from salmon canning processes. | production of protease by fermentation, using sorangium 495, of a substrate based on condensed fish solubles is demonstrated. the effects of carbohydrate addition, ph, fish solubles concentration, scale-up, agitation, and air flow rate on protease yields are described. while the fish solubles medium alone could give rise to measurable yields of protease, these were, at worst, doubled when 1% glucose was added to the medium. ph 7 was optimal for protease yield. although the concentration of fish ... | 1980 | 6780175 |
| the tartrolons, new boron-containing antibiotics from a myxobacterium, sorangium cellulosum. | new antibiotics were isolated from the culture broth of the myxobacterium, sorangium cellulosum, strain so ce 678. the antibiotics were active against gram-positive bacteria and mammalian cells. they were named tartrolon a and b. tartrolon b contains a boron atom. the boron binding region of tartrolon is identical with that of boromycin and aplasmomycin. | 1995 | 7532644 |
| the ripostatins, novel inhibitors of eubacterial rna polymerase isolated from myxobacteria. | a new antibiotic, ripostatin, was isolated from the culture supernatant of the myxobacterium, sorangium cellulosum strain so ce377. it is a macrocyclic lactone carbonic acid containing an unsubstituted phenyl ring in a side chain. the antibiotic acts especially on staphylococcus aureus, but seems not to penetrate most bacteria. the mic values are in the range of 1 microgram/ml. ripostatin is an inhibitor of eubacterial rna polymerase. it interferes with the initiation of rna synthesis. | 1995 | 7592022 |
| sorangiolid a, a new antibiotic isolated from the myxobacterium sorangium cellulosum so ce 12. | | 1995 | 7592035 |
| chivosazol a, a new inhibitor of eukaryotic organisms isolated from myxobacteria. | a new antibiotic, chivosazol, was isolated from the culture broth of the myxobacterium sorangium cellulosum strain so ce12. it is a macrocyclic ring with one oxazol ring and a glycosidically bound 6-deoxyglucose (quinovose) at c-11. the antibiotic shows antimicrobial activity against yeasts and filamentous fungi, and is especially potent against mammalian cells. it was not active against bacteria. | 1995 | 7592063 |
| ratjadon: a new antifungal compound from sorangium cellulosum (myxobacteria) production, physio-chemical and biological properties. | an antifungal activity, ratjadon, was detected in the culture broth of sorangium cellulosum (myxococcales) strain so ce360. the metabolite was quantitatively bound to the adsorber resin xad-16, which was added to the medium at the beginning of the fermentation. the antibiotic spectrum was narrow, but some important phytopathogenic fungi, especially species of oomycetes, were inhibited at very low concentrations. | 1995 | 7592065 |
| a sorangium cellulosum (myxobacterium) gene cluster for the biosynthesis of the macrolide antibiotic soraphen a: cloning, characterization, and homology to polyketide synthase genes from actinomycetes. | a 40-kb region of dna from sorangium cellulosum so ce26, which contains polyketide synthase (pks) genes for synthesis of the antifungal macrolide antibiotic soraphen a, was cloned. these genes were detected by homology to streptomyces violaceoruber genes encoding components of granaticin pks, thus extending this powerful technique for the identification of bacterial pks genes, which has so far been applied only to actinomycetes, to the gram-negative myxobacteria. functional analysis by gene disr ... | 1995 | 7601830 |
| disorazol a, an efficient inhibitor of eukaryotic organisms isolated from myxobacteria. | a new antibiotic, disorazol, was isolated from the culture broth of the myxobacterium, sorangium cellulosum strain so ce 12. it is a macrocyclic compound containing two oxazole rings. the antibiotic acted against many fungi and mammalian cell cultures. the latter responded to extremely low doses (mic 3-30 pg/ml). none of the tested bacteria and yeasts were inhibited. | 1995 | 7868386 |
| identification of the yeast acc1 gene product (acetyl-coa carboxylase) as the target of the polyketide fungicide soraphen a. | soraphen a, a polyketide isolated from the myxobacterium sorangium cellulosum, is a potent inhibitor of fungal growth. we have used a genetic approach to localize the target of this drug, employing saccharomyces cerevisiae as a model organism. we have isolated soraphen a-resistant mutants and found that all of them map at the same genetic locus and exhibit a broad range of semidominant phenotypes. data from genetic crosses of soraphen a-resistant clones with an acc1 mutant revealed that acc1, co ... | 1994 | 7916271 |
| the soraphens: a family of novel antifungal compounds from sorangium cellulosum (myxobacteria). i. soraphen a1 alpha: fermentation, isolation, biological properties. | an antifungal activity was detected in the culture broth of sorangium cellulosum (myxococcales), strain so ce26. the activity was excreted into the supernatant during the log and early stationary phase. the active substance was quantitatively bound to xad absorber resin added to the medium at the beginning of the fermentation. the new secondary metabolite was called soraphen and is of special interest to plant disease control for its inhibitory activity against numerous phytopathogenic fungi. | 1994 | 8119858 |
| the jerangolids: a family of new antifungal compounds from sorangium cellulosum (myxobacteria). production, physico-chemical and biological properties of jerangolid a. | an antifungal activity was detected in the culture broth of the myxobacterium, sorangium cellulosum strain so ce 307. the activity was excreted into the supernatant during the log and early stationary phase. when the organism was fermented in the presence of the adsorber resin xad-16, the metabolite was quantitatively bound to the resin. the main component, jerangolid a, has structural similarities to ambruticin, which is also produced by strains of sorangium cellulosum. | 1996 | 8609090 |
| epothilons a and b: antifungal and cytotoxic compounds from sorangium cellulosum (myxobacteria). production, physico-chemical and biological properties. | an antifungal activity against mucor hiemalis was detected in the culture broth of sorangium cellulosum (myxococcales) strain so ce90. the activity was excreted into the supernatant during the log and early stationary phase. when the adsorber resin xad-16 was added to the culture, the active metabolites were quantitatively bound to the resin. the epothilons showed a high cytotoxicity for animal cells and mimic the biological effects of taxol (bollag et al., cancer res. 55: 2325 approximately 233 ... | 1996 | 8698639 |
| synthesis of epothilones a and b in solid and solution phase. | epothilones a and b, two compounds that have been recently isolated from myxobacterium sorangium cellulosum strain 90, have generated intense interest among chemists, biologists and clinicians owing to the structural complexity, unusual mechanism of interaction with microtubules and anticancer potential of these molecules. like taxol, they exhibit cytotoxicity against tumour cells by inducing microtubule assembly and stabilization, even in taxol-resistant cell lines. following the structural elu ... | 1997 | 9153390 |
| epothilone b stabilizes microtubuli of macrophages like taxol without showing taxol-like endotoxin activity. | epothilones are a new class of potential antitumor compounds that were isolated from the myxobacterium sorangium cellulosum. epothilones have effects on the cytoskeleton similar to those of the antineoplastic drug taxol. both compounds inhibit cell proliferation by stabilizing microtubuli, and they compete for the same binding site. in addition, taxol displays endotoxin-like properties in that it activates macrophages to synthesize proinflammatory cytokines and nitric oxide. we measured nitric o ... | 1997 | 9269992 |
| metabolic diversity in myxobacteria: identification of the myxalamid and the stigmatellin biosynthetic gene cluster of stigmatella aurantiaca sg a15 and a combined polyketide-(poly)peptide gene cluster from the epothilone producing strain sorangium cellulosum so ce90. | myxobacterial strains producing polyketides (pks) assumed to be biosynthesized by a type i polyketide synthase (pks) were analysed. myxobacteria also produce a variety of polypeptides (pp) and pks with incorporated amino acids ('mixed pk-pp'). in order to be able to identify the biosynthetic gene clusters for these metabolites a pcr based approach has been developed to clone ketosynthase (ks) domains of pks genes from these organisms. conserved regions of peptide synthetases of the non-ribosomal ... | 1999 | 10320771 |
| the correlation between morphological and phylogenetic classification of myxobacteria. | in order to determine whether morphological criteria are suitable to affiliate myxobacterial strains to species, a phylogenetic analysis of 16s rdnas was performed on 54 myxobacterial strains that represented morphologically 21 species of the genera angiococcus, archangium, chondromyces, cystobacter, melittangium, myxococcus, polyangium and stigmatella, five invalid species and three unclassified isolates. the analysis included 12 previously published sequences. the branching pattern confirmed t ... | 1999 | 10425789 |
| cloning and heterologous expression of the epothilone gene cluster. | the polyketide epothilone is a potential anticancer agent that stabilizes microtubules in a similar manner to taxol. the gene cluster responsible for epothilone biosynthesis in the myxobacterium sorangium cellulosum was cloned and completely sequenced. it encodes six multifunctional proteins composed of a loading module, one nonribosomal peptide synthetase module, eight polyketide synthase modules, and a p450 epoxidase that converts desoxyepothilone into epothilone. concomitant expression of the ... | 2000 | 10649995 |
| the biosynthetic gene cluster for the microtubule-stabilizing agents epothilones a and b from sorangium cellulosum so ce90. | epothilones are produced by the myxobacterium sorangium cellulosum so ce90, and, like paclitaxel (taxol((r))), they inhibit microtubule depolymerisation and arrest the cell cycle at the g2-m phase. they are effective against p-glycoprotein-expressing multiple-drug-resistant tumor cell lines and are more water soluble than paclitaxel. the total synthesis of epothilones has been achieved, but has not provided an economically viable alternative to fermentation. we set out to clone, sequence and ana ... | 2000 | 10662695 |
| an approach for obtaining perfect hybridization probes for unknown polyketide synthase genes: a search for the epothilone gene cluster. | an approach is described for obtaining 'perfect probes' for type i modular polyketide synthase (pks) gene clusters that in turn enables the identification of all such gene clusters in a genome. the approach involves sequencing small fragments of a random genomic dna library containing one or more modular pks gene clusters, and identifying which fragments emanate from pks genes. knowing the approximate sizes of the genome and the target gene cluster, one can predict the the frequency that a pks g ... | 2000 | 10773448 |
| identification of an l-dopa decarboxylase gene from sorangium cellulosum so ce90. | during a screening program intended to identify genes encoding enzymes typical for secondary metabolism in sorangium cellulosum so ce90, an aromatic amino acid decarboxylase gene (ddc) was detected. expression of ddc in escherichia coli and subsequent enzyme assays with cell-free extracts confirmed the proposed function derived from amino acid sequence comparisons. in contrast to other aromatic amino acid decarboxylases of eukaryotic origin, the s. cellulosum ddc converted only l-dihydroxy pheny ... | 2000 | 10816050 |
| isolation and characterization of the epothilone biosynthetic gene cluster from sorangium cellulosum. | the epothilone biosynthetic gene cluster was isolated from sorangium cellulosum strain smp44. the gene cluster contains seven genes and spans approx. 56kb. the genes encoding the pks, epoa, epoc, epod, epoe, and epof, are divided into nine modules. the epob protein is a non-ribosomal peptide synthetase (nrps) that catalyzes formation of the thiazole found in the epothilones. epok is a p450 enzyme responsible for the epoxidation of epothilones c and d to epothilones a and b, respectively. epok wa ... | 2000 | 10831849 |
| the mtaa gene of the myxothiazol biosynthetic gene cluster from stigmatella aurantiaca dw4/3-1 encodes a phosphopantetheinyl transferase that activates polyketide synthases and polypeptide synthetases. | myxothiazol is synthesized by the myxobacterium stigmatella aurantiaca dw4/3-1 via a combined polyketide synthase/polypeptide synthetase. the biosynthesis of this secondary metabolite is also dependent on the gene product of mtaa. the deduced amino acid sequence of mtaa shows similarity to 4'-phosphopantetheinyl transferases (4'-pp transferase). this points to an enzyme activity that converts inactive forms of the acyl carrier protein domains of polyketide synthetases (pkss) and/or the peptidyl ... | 2001 | 11134965 |
| in vivo metabolism of epothilone b in tumor-bearing nude mice: identification of three new epothilone b metabolites by capillary high-pressure liquid chromatography/mass spectrometry/tandem mass spectrometry. | epothilone b is a 16-membered macrolide produced by the myxobacterium sorangium cellulosum and is currently under clinical investigation. experimentally, epothilone b demonstrates potent antiproliferative activity at the nanomolar level in vitro, and potent regression-producing antitumor activity in vivo, similar to paclitaxel (taxol). in order to foster the design of improved derivatives, the potential biotransformation products of epothilone b formed in liver of tumor-bearing mice after intrav ... | 2001 | 11135423 |
| studies on the biosynthesis of epothilones: the biosynthetic origin of the carbon skeleton. | the biosynthetic origin of the epothilone skeleton was studied by the incorporation of 13c and radioactively labeled precursors by sorangium cellulosum so ce90. the carbon atoms are derived from acetate, propionate, the methyl group of s-adenosyl-methionine, and cysteine which also introduces the sulfur and nitrogen atoms. epothilone biosynthesis starts with the formation of the thiazole part from acetate and cysteine. the incorporation of acetate or propionate units results in the formation of ... | 2000 | 11217802 |
| new natural epothilones from sorangium cellulosum, strains so ce90/b2 and so ce90/d13: isolation, structure elucidation, and sar studies. | in addition to epothilones a (1) and b (2), 37 natural epothilone variants and epothilone-related compounds were isolated from the culture broth of a 700 l fermentation of sorangium cellulosum, strain so ce90/b2. of these, only the 12,13-desoxyepothilones, epothilone c (14) and d (15), were produced in significant amounts (3-6 mg/l); the 21-hydroxy derivatives and epothilones e (3) and f (4), in low and variable amounts due to further degradation by the producing organism. most of the other epot ... | 2001 | 11473410 |
| epothilone biosynthesis: assembly of the methylthiazolylcarboxy starter unit on the epob subunit. | polyketides (pks) and non-ribosomal peptides (nrps) are therapeutically important natural products biosynthesized by multimodular protein assembly lines, termed the pk synthases (pkss) and nrp synthetases (nrpss), via a similar thiotemplate-mediated mechanism. the potential for productive interaction between these two parallel enzymatic systems has recently been demonstrated, with the discovery that pk/nrp hybrid natural products can be of great therapeutic importance. one newly discovered pk/nr ... | 2001 | 11564558 |
| chain initiation on the soraphen-producing modular polyketide synthase from sorangium cellulosum. | polyketides are structurally diverse natural products with a wide range of useful activities. bacterial modular polyketide synthases (pkss) catalyse the production of non-aromatic polyketides using a different set of enzymes for each successive cycle of chain extension. the choice of starter unit is governed by the substrate specificity of a distinct loading module. the unusual loading module of the soraphen modular pks, from the myxobacterium sorangium cellulosum, specifies a benzoic acid start ... | 2001 | 11755398 |
| production of an exopolysaccharide bioflocculant by sorangium cellulosum. | to isolate a new exopolysaccharide bioflocculant produced by the myxobacterium sorangium cellulosum nust06, and to characterize its chemical composition and expolysaccharide production relative to carbon source. | 2002 | 11874538 |
| studies on the biosynthesis of epothilones: hydroxylation of epo a and b to epothilones e and f. | when sorangium cellulosum so ce90 is grown without xad adsorber resin there is a steady state of epothilone a and b biosynthesis and hydroxylation of these products to epothilones e and f. this biotransformation at position c-21 of the thiazole ring is not restricted to producers of epothilones. it is carried out by a substrate induced monooxygenase. epothilones e and f are further degraded by opening of the lactone ring by an esterase. steps of degradation of different strains of s. cellulosum ... | 2002 | 11918064 |
| characterization of the biosynthetic gene cluster for the antifungal polyketide soraphen a from sorangium cellulosum so ce26. | a genomic dna region of over 80 kb that contains the complete biosynthetic gene cluster for the synthesis of the antifungal polyketide metabolite soraphen a was cloned from sorangium cellulosum so ce26. the nucleotide sequence of the soraphen a gene region, including 67,523 bp was determined. examination of this sequence led to the identification of two adjacent type i polyketide synthase (pks) genes that encode the soraphen synthase. one of the soraphen a pks genes includes three biosynthetic m ... | 2002 | 12039053 |
| epothilones: a novel class of non-taxane microtubule-stabilizing agents. | the epothilones are a novel class of non-taxane microtubule-stabilizing agents obtained from the fermentation of the cellulose degrading myxobacteria, sorangium cellulosum. preclinical studies have shown that the epothilones are more potent than the taxanes and active in some taxane-resistant models. similar to paclitaxel and other taxanes, the epothilones block cells in mitosis, resulting in cell death. the chief components of the fermentation process are epothilones a and b, with epothilones c ... | 2002 | 12171542 |
| heterologous expression of epothilone biosynthetic genes in myxococcus xanthus. | epothilones are potential anticancer drugs that stabilize microtubules in a manner similar to paclitaxel (taxol). epothilones are produced from the myxobacterium sorangium cellulosum, which has a 16-h doubling time and produces only milligram-per-liter amounts of epothilone a and epothilone b. furthermore, genetic manipulation of s. cellulosum is difficult. to produce epothilones in a more genetically amenable and rapidly growing host, we chose the closely related and best-characterized myxobact ... | 2002 | 12183227 |
| utilization of alternate substrates by the first three modules of the epothilone synthetase assembly line. | the epothilones, a family of macrolactone natural products produced by the myxobacterial species sorangium cellulosum, are of current clinical interest as antitumor agents. inspection of the structure of the epothilones suggests a hybrid polyketide/nonribosomal peptide biosynthetic origin, and the recent sequencing of the epothilone biosynthetic gene cluster has validated this proposal. here we have examined unnatural substrates with the first two enzymes of the biosynthetic pathway, epoa and ep ... | 2002 | 12236733 |
| recent developments in the chemistry, biology and medicine of the epothilones. | the epothilones have occupied center stage on the scenes of total synthesis, chemical biology and medicine for the last five years, no doubt because of their intriguing mode of action and unusually high potency against tumor cells, including multidrug-resistant cell lines. this article highlights the most recent advances within this exciting field. thus, an overview of recent synthetic endeavors culminating in a new generation of total syntheses and analogues, some with higher potencies than the ... | 2001 | 12240368 |
| characterisation, genome size and genetic manipulation of the myxobacterium sorangium cellulosum so ce56. | in this study, sorangium cellulosum so ce56 was phenotypically and genotypically analysed in order to evaluate whether this strain can be used in a comprehensive genome project as a representative of the secondary metabolite-producing myxobacteria. in contrast to many other strains of s. cellulosum, strain so ce56 was found to have various advantageous features, including fast and homogeneous growth in submerged cultures and the ability to complete its morphological differentiation cycle on agar ... | 2002 | 12420170 |
| mutations in beta-tubulin map to domains involved in regulation of microtubule stability in epothilone-resistant cell lines. | the epothilones (epos) are a group of natural products isolated from the myxobacterium, sorangium cellulosum. they have a mechanism of action similar to that of taxol, i.e., they stabilize microtubules and induce the formation of microtubule bundles in cells. because they are simpler in structure than taxol and preserve their activity in p-glycoprotein-expressing cells, they are being studied as potential antitumor drugs. in this work, a series of epo-resistant a549 and hela cell lines have been ... | 2001 | 12467233 |
| [isolation and identification of myxobacteria]. | this paper reported that the authors isolated large numbers of myxobacteria from more than 100 samples collected in many places of china. more than 400 pure strains were obtained. these strains belonged to 10 genera of myxococcales. the most frequent genera isolated were myxococcus, sorangium, corallococcus, and cystobacter. melittangium was seldom isolated. no chondromyces and haploangium were found. | 2000 | 12549062 |
| [diversity of metabolites and their bio-activities in myxobacterium sorangium cellulosum]. | different sorangium cellulosum strains not only showed diversity in their cell and fruiting body morphologies, but also differences of bio-activities and components of the metabolites. all the sorangial strains studied in this paper had no activity on gram-negative bacteria, some were able to repress gram-positive bacteria. however, all the strains were able to repress growth of fungi and tumor cells strongly and widely. thin layer chromatography assay of metabolites showed multi-components in t ... | 2001 | 12552829 |
| multi parameter in vitro testing of ratjadone using flow cytometry. | ratjadone, isolated from the myxobacterium sorangium cellulosum, belongs to the family of so-called orphan ligands, which includes leptomycin, callystatin and other compounds. in previous screening tests, ratjadone revealed a growth inhibitory effect against bacteria, yeast and human cancer cells. following these first results, ratjadone was tested on several human tumour cell lines (jurkat, hepg2, u87-mg) and, as a control, on a non-tumour cell line (rlc18) for its mode of action. the cell anal ... | 2003 | 12679852 |
| polyketide-nonribosomal peptide epothilone antitumor agents: the epoa, b, c subunits. | the epothilones are a family of macrolactone natural products from the myxobacterial species sorangium cellulosum. similar to taxol, they are of current clinical interest as anticancer agents. sequence analysis of the epothilone gene cluster allowed the identification of polyketide synthase and nonribosomal peptide synthetase modules involved in catalyzing epothilone biosynthesis. given this information, it has been possible to test the predicted functions of several modules to date. epoa acp, e ... | 2003 | 12707798 |
| morphologies and phylogenetic classification of cellulolytic myxobacteria. | the evolutionary distances of the 16s rdna sequences in cellulolytic myxobacteria are less than 3%, which units all the strains into a single genus, sorangium. the size of myxospores and the shape of sporangioles, rather than fruiting body colors or swarm morphologies are consistent with the changes of the 16s rdna sequences. it is suggested that there are at least two species in the genus sorangium: one includes strains with small myxospores and spherical sporangioles, and the color of the frui ... | 2003 | 12747417 |
| ratjadones inhibit nuclear export by blocking crm1/exportin 1. | in addition to previously isolated ratjadone a we describe three new members of this family, ratjadones b, c, and d, from another strain of the myxobacterium sorangium cellulosum. we have investigated the properties of these ratjadones with respect to their activity on mammalian cell lines. we found ic(50) values in the picomolar range and a significant increase in the size of nuclei. a further examination showed that they inhibit the export of the leucine-rich nuclear export signal (lr-nes) con ... | 2003 | 12749860 |
| nutrient regulation of epothilone biosynthesis in heterologous and native production strains. | fermentation media with different initial concentrations of ammonium and phosphate salts were used to study the inhibitory effects of those ions on growth and production of epothilone in sorangium cellulosum and myxococcus xanthus. the native epothilone producer, s. cellulosum was more sensitive to ammonium and phosphate than the heterologous producer, m. xanthus. an ammonium concentration of 12 mm reduced epothilone titers by 90% in s. cellulosum but by only 40% in m. xanthus. when 5 mm phospha ... | 2003 | 12764559 |
| 16s-23s ribosomal dna intergenic spacer regions in cellulolytic myxobacteria and differentiation of closely related strains. | the diversity of 16s-23s rdna intergenic spacer regions (isr) among cellulolytic myxobacterial strains was assayed. agarose gel electrophoresis of pcr amplification products from ten strains shows that there are at least four copies of rrna operons in the genus sorangium, based on their size and restriction enzymatic digest maps. there are two sequence organization patterns: trna(ile)-trna(ala)-containing isr and trna-lacking isr. the trna-containing isrs are highly similar among strains and wit ... | 2003 | 12866853 |
| crystal structures of epothilone d-bound, epothilone b-bound, and substrate-free forms of cytochrome p450epok. | epothilones are potential anticancer drugs that stabilize microtubules by binding to tubulin in a manner similar to paclitaxel. cytochrome p450epok (p450epok), a heme containing monooxygenase involved in epothilone biosynthesis in the myxobacterium sorangium cellulosum, catalyzes the epoxidation of epothilones c and d into epothilones a and b, respectively. the 2.10-, 1.93-, and 2.65-a crystal structures reported here for the epothilone d-bound, epothilone b-bound, and substrate-free forms, resp ... | 2003 | 12933799 |
| extracellular enzymes from strains of sorangium. | | 1965 | 14290951 |
| [description of some new species and varieties of cellulose-decomposing myxobacteria]. | | 1962 | 14488956 |
| the leupyrrins: a structurally unique family of secondary metabolites from the myxobacterium sorangium cellulosum. | the structurally unique leupyrrins a1 (1), a2 (2), b1 (3), b2 (4), c (5), and d (6) were isolated as one of three groups of secondary metabolites from sorangium cellulosum strains so ce705 and so ce690. an unusually substituted gamma-butyrolactone ring and pyrrole and oxazoline rings are embedded in a nonsymmetric macrodiolide core structure, giving rise to compounds 1-6 as members of a novel class of secondary metabolites. leupyrrin a1 (1) shows good biological activity against various fungi an ... | 2003 | 14510597 |
| development of a mariner-based transposon for use in sorangium cellulosum. | in order to generate marked insertions in the myxobacterium sorangium cellulosum, a transposon based on the eukaryotic mariner transposon was developed. the transposition frequency was increased with the use of a mutated tnp gene. the transposon randomly inserts into the chromosome, as demonstrated by targeted mutagenesis of the epok gene. | 2003 | 14532095 |
| naturally mosaic operons for secondary metabolite biosynthesis: variability and putative horizontal transfer of discrete catalytic domains of the epothilone polyketide synthase locus. | a putative instance of horizontal gene transfer (hgt) involving adjacent, discrete beta-ketoacyl synthase (ks), acyl carrier protein (acp) and nonribosomal peptide synthase (nrps) domains of the epothilone type i polyketide biosynthetic gene cluster from the myxobacterium sorangium cellulosom was identified using molecular phylogenetics and sequence analyses. the specific ks domain of the module epo b fails to cluster phylogenetically with other epothilone ks sequences present at this locus, in ... | 2003 | 14595556 |
| whole genome shotgun sequencing guided by bioinformatics pipelines--an optimized approach for an established technique. | while the sequencing of bacterial genomes has become a routine procedure at major sequencing centers, there are still a number of genome projects at small- or medium-size facilities. for these facilities a maximum of control over sequencing, assembling and finishing is essential. at the same time, facilities have to be able to co-operate at minimum costs for the overall project. we have established a pipeline for the distributed sequencing of alcanivorax borkumensis sk2, azoarcus sp. bh72, clavi ... | 2003 | 14651855 |
| myxobacteria: proficient producers of novel natural products with various biological activities--past and future biotechnological aspects with the focus on the genus sorangium. | myxobacteria are gram-negative bacteria which are most noted for their ability to form fruiting bodies upon starvation. within the last two decades, they increasingly gained attention as producers of natural products with biological activity. here, recent and future biotechnological research on certain key myxobacteria and on their ability to produce natural products is reviewed with the focus on the production of myxovirescin, soraphen and epothilone. aspects of product improvement and yield as ... | 2003 | 14651865 |
| critical variations of conjugational dna transfer into secondary metabolite multiproducing sorangium cellulosum strains so ce12 and so ce56: development of a mariner-based transposon mutagenesis system. | myxobacteria increasingly gain attention as a source of bioactive natural products. the genus sorangium produces almost half of the secondary metabolites isolated from these microorganisms. nevertheless, genetic systems for sorangium strains are poorly developed, which makes the identification of the genes directing natural product biosynthesis difficult. using biparental and triparental mating, we have developed methodologies for dna transfer from escherichia coli via conjugation for the genome ... | 2004 | 14687969 |
| elucidating the mechanism of cis double bond formation in epothilone biosynthesis. | the epothilones, originally isolated from the myxobacterium sorangium cellulosum, are macrocyclic compounds that are synthesized by a modular polyketide synthase, an enzyme complex composed of six large, multifunctional proteins. the penultimate intermediates in epothilone production, and the products of the pks-catalyzed reactions, are epothilones d and c, which contain a 12,13-cis-double bond. the 12 and 13 positions of epothilones are generated during the fourth elongation step that is govern ... | 2004 | 14709052 |
| structural features and hypoglycaemic activity of an exopolysaccharide produced by sorangium cellulosum. | to investigate the structural features and hypoglycaemic activity of an exopolysaccharide (eps) produced by sorangium cellulosum nust06. | 2004 | 14962044 |
| a new dominant selection marker for transformation of pichia pastoris to soraphen a resistance. | despite the considerable progress molecular genetics of filamentous fungi has made during the past decade, there is still an urgent need for efficiently working selectable markers for fungal transformation. using pichia pastoris as a host, we describe the development of a new dominant selectable marker of prokaryotic origin. this system, termed sor(r), is based upon the resistance of the bacterial enzyme acetyl-coa carboxylase (accase) to the macrocyclic polyketide soraphen a, a potent inhibitor ... | 2004 | 15003686 |
| disorazol a1, a highly effective antimitotic agent acting on tubulin polymerization and inducing apoptosis in mammalian cells. | disorazol a1, a macrocyclic polyketide compound that is produced by the myxobacterium sorangium cellulosum showed a remarkably high cytostatic activity. it inhibited the proliferation of different cancer cell lines including a multidrug-resistant kb line at low picomolar levels. in presence of disorazol a1, the nuclei of the cells increased in size and the cells often became multinucleate. low concentrations of disorazol (<100 pm) induced an apoptotic process, characterized by enhanced capase-3 ... | 2004 | 15104246 |
| heterologous production of the antifungal polyketide antibiotic soraphen a of sorangium cellulosum so ce26 in streptomyces lividans. | the antifungal polyketide soraphen a is produced by the myxobacterium sorangium cellulosum so ce26. the slow growth, swarming motility and general intransigence of the strain for genetic manipulations make industrial strain development, large-scale fermentation and combinatorial biosynthetic manipulation of the soraphen producer very challenging. to provide a better host for soraphen a production and molecular engineering, the biosynthetic gene cluster for this secondary metabolite was integrate ... | 2004 | 15289572 |
| unusual biosynthesis of leupyrrins in the myxobacterium sorangium cellulosum. | | 2004 | 15307077 |
| total synthesis of (-)-disorazole c1. | the antimitotic natural product disorazole c1 was isolated in 1994 from the fermentation broth of the myxobacterium sorangium cellulosum. we have developed a highly convergent and stereoselective total synthesis of this compound which establishes its relative and absolute configuration. key features of our synthesis include a highly convergent strategy and selective functional group manipulations that minimize decomposition of the sensitive polyene macrodiolide. | 2004 | 15563138 |
| novel insights into siderophore formation in myxobacteria. | the myxochelins are catecholate-type siderophores produced by a number of myxobacterial strains, and their corresponding biosynthetic gene clusters have been identified in stigmatella aurantiaca sg a15, and sorangium cellulosum so ce56; the latter being presented in this work. biochemical and genetic studies described here further clarify myxochelin biosynthesis. in addition to the myxochelin a biosynthetic complex, the aminotransferase mxcl is required in order to form myxochelin b, starting fr ... | 2005 | 15678426 |
| production of the tubulin destabilizer disorazol in sorangium cellulosum: biosynthetic machinery and regulatory genes. | myxobacteria show a high potential for the production of natural compounds that exhibit a wide variety of antibiotic, antifungal, and cytotoxic activities. the genus sorangium is of special biotechnological interest because it produces almost half of the secondary metabolites isolated from these microorganisms. we describe a transposon-mutagenesis approach to identifying the disorazol biosynthetic gene cluster in sorangium cellulosum so ce12, a producer of multiple natural products. in addition ... | 2005 | 15892181 |
| epothilone d affects cell cycle and microtubular pattern in plant cells. | epothilones, macrocyclic lactones from culture filtrates of the myxobacterium sorangium cellulosum, are known as taxol-like microtubular drugs in human medicine. to date, nothing is known about the effect of epothilones on microtubules (mts) in plant cells and/or on the plant cell cycle. as shown in this report, the treatment of tomato cell suspension cultures with epothilone d produced a continuous increase in the mitotic index. dose-response curves revealed that epothilone d alters the mitotic ... | 2005 | 15967777 |
| [the pks/nrps hetero-gene cluster of epothilones]. | novel macrolides epothilones, produced by cellulolytic myxobacterium sorangium cellulosum, have the activity to promote microtubule assembly, and are considered to be a potential successor to the famous antitumor drug taxol. the biosynthetic genes leading to the epothilones are clustered into a large operon. the multi-enzyme complex is a hetero-gene cluster of polyketide synthase (pks) and non-ribosomal peptide synthetases (nrps) and contains several functional modules, i.e. a loading module, on ... | 2003 | 15969075 |
| the biosynthetic genes for disorazoles, potent cytotoxic compounds that disrupt microtubule formation. | disorazoles are polyketides produced by the myxobacterium sorangium cellulosum so ce12. their mode of action is to inhibit tubulin polymerization and destabilize microtubules. using transposon mutagenesis, two mutant strains were identified that produced no disorazoles. sequencing the dna flanking the insertions revealed a polyketide synthase gene cluster that would encode three polypeptides, dsza, dszb, and dszc, with dszc containing both nonribosomal peptide synthetase and polyketide synthase ... | 2005 | 16084035 |
| cloning, sequence analysis and disruption of the mgla gene involved in swarming motility of sorangium cellulosum so ce26, a producer of the antifungal polyketide antibiotic soraphen a. | the myxobacterium sorangium cellulosum so ce26, the producer of the agriculturally important fungicide antibiotic soraphen a, displays coordinated gliding motility (swarming) on agar surfaces. the consequent failure to form detached colonies represents a major obstacle for microbiological and genetic studies, since single cells representing discrete genetic events cannot be reliably separated and propagated as clones. the mgla protein, the product of the mgla gene, has been shown to be a central ... | 2004 | 16233626 |
| identification and analysis of the chivosazol biosynthetic gene cluster from the myxobacterial model strain sorangium cellulosum so ce56. | myxobacteria belonging to the genus sorangium are known to produce a variety of biologically active secondary metabolites. chivosazol is a macrocyclic antibiotic active against yeast, filamentous fungi and especially against mammalian cells. the compound specifically destroys the actin skeleton of eucaryotic cells and does not show activity against bacteria. chivosazol contains an oxazole ring and a glycosidically bound 6-deoxyglucose (except for chivosazol f). in this paper we describe the bios ... | 2006 | 16313990 |
| development of simple media which allow investigations into the global regulation of chivosazol biosynthesis with sorangium cellulosum so ce56. | media, completely different with respect to their complexity, were investigated for growth and secondary metabolism with sorangium cellulosum strain so ce56. while technical substrates are best for metabolite production, these media are not suitable to study gene expressions. free amino acids as present in soluble media based on peptones were found to inhibit polyketide biosynthesis. therefore synthetic growth and production media were developed. different nitrogen- and carbon sources as well as ... | 2006 | 16321454 |
| establishment of a real-time pcr protocol for expression studies of secondary metabolite biosynthetic gene clusters in the g/c-rich myxobacterium sorangium cellulosum so ce56. | in the attempt to establish a reliable real-time pcr protocol for transcriptional analysis of secondary metabolism in sorangium cellulosum strain so ce56, a rna extraction method and a reverse transcription protocol was developed. in order to validate chivosazol or etnangien gene cluster transcripts as good candidates to develop the real-time pcr protocol, stability measurements of the transcripts were performed proving both transcripts to be very stable. the chivosazol biosynthetic gene cluster ... | 2006 | 16324759 |
| bacterial type iii polyketide synthases: phylogenetic analysis and potential for the production of novel secondary metabolites by heterologous expression in pseudomonads. | type iii polyketide synthases (pks) were regarded as typical for plant secondary metabolism before they were found in microorganisms recently. due to microbial genome sequencing efforts, more and more type iii pks are found, most of which of unknown function. in this manuscript, we report a comprehensive analysis of the phylogeny of bacterial type iii pks and report the expression of a type iii pks from the myxobacterium sorangium cellulosum in pseudomonads. there is no precedent of a secondary ... | 2006 | 16395556 |
| heterologous production of epothilone c and d in escherichia coli. | the epothilones are a family of polyketide natural products that show a high potential as anticancer drugs. they are synthesized by the action of a hybrid nonribosomal peptide synthetase/polyketide synthase in the myxobacterium sorangium cellulosum. in this work, the genes encoding the entire cluster,epoa, epob, epoc, epod, epoe, and epof, were redesigned and synthesized to allow for expression in escherichia coli. the expression of the largest of the proteins, epod, also required the protein be ... | 2006 | 16430229 |