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Pierre Leblond - One of the best experts on this subject based on the ideXlab platform.
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An aminoacylase activity from Streptomyces ambofaciens catalyzes the acylation of lysine on α-position and peptides on N-terminal position
Engineering in Life Sciences, 2018Co-Authors: Léna Dettori, Pierre Leblond, Laurence Hotel, Florent Ferrari, Xavier Framboisier, Cédric Paris, Yann Guiavarc'h, Arnaud Aymes, Catherine Humeau, Romain KapelAbstract:The presence of aminoacylase activities was investigated in a crude extract of Streptomyces ambofaciens ATCC23877. First activities catalyzing the hydrolysis of N-alpha or epsilon-acetyl-L-lysine were identified. Furthermore, the acylation of lysine and different peptides was studied and compared with results obtained with lipase B of Candida antarctica (CALB). Different regioselectivities were demonstrated for the two classes of enzymes. CALB was able to catalyze acylation only on the epsilon-position whereas the crude extract from S. ambofaciens possessed the rare ability to catalyze the N-acylation on the alpha-position of the lysine or of the amino-acid in N-terminal position of peptides. Two genes, SAM23877_1485 and SAM23877_1734, were identified in the genome of Streptomyces ambofaciens ATCC23877 whose products show similarities with the previously identified aminoacylases from Streptomyces mobaraensis. The proteins encoded by these two genes were responsible for the major aminoacylase hydrolytic activities. Furthermore, we show that the hydrolysis of N-alpha-acetyl-L-lysine could be attributed to the product of SAM23877_1734 gene.
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Implication of RuvABC and RecG in homologous recombination in Streptomyces ambofaciens
Research in Microbiology, 2017Co-Authors: Gregory Hoff, Annabelle Thibessard, Claire Bertrand, Emilie Piotrowski, Pierre LeblondAbstract:Most bacterial organisms rely on homologous recombination to repair DNA double-strand breaks and for the post-replicative repair of DNA single-strand gaps. Homologous recombination can be divided into three steps: (i) a pre-synaptic step in which the DNA 3'-OH ends are processed, (ii) a recA-dependent synaptic step allowing the invasion of an intact copy and the formation of Holliday junctions, and (iii) a post synaptic step consisting of migration and resolution of these junctions. Currently, little is known about factors involved in homologous recombination, especially for the post-synaptic step. In Escherichia coli, branch migration and resolution are performed by the RuvABC complex, but could also rely on the RecG helicase in a redundant manner. In this study, we show that recG and ruvABC are well-conserved among Streptomyces. AruvABC, ArecG and AruvABC ArecG mutant strains were constructed. A ruvABC A recG is only slightly affected by exposure to DNA damage (UV). We also show that conjugational recombination decreases in the absence of RuvABC and RecG, but that intrachromosomal recombination is not affected. These data suggest that RuvABC and RecG are indeed involved in homologous recombination in Streptomyces ambofaciens and that alternative factors are able to take over Holliday junction in Streptomyces.
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complete genome sequence of Streptomyces ambofaciens dsm 40697 a paradigm for genome plasticity studies
Genome Announcements, 2016Co-Authors: Pierre Leblond, Annabelle ThibessardAbstract:The sequence of Streptomyces ambofaciens DSM 40697 was completely determined. The genome consists of an 8.1-Mbp linear chromosome with terminal inverted repeats of 210 kb. Genomic islands were identified, one of which corresponds to a new putative integrative and conjugative element (ICE) called pSAM3.
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Complete genome sequence of Streptomyces ambofaciens ATCC 23877, the spiramycin producer
Journal of Biotechnology, 2015Co-Authors: Annabelle Thibessard, Bertrand Aigle, Jean-luc Pernodet, Sylvie Lautru, Drago Haas, Claude Gerbaud, Pierre LeblondAbstract:Streptomyces ambofaciens ATCC23877 is a soil bacterium industrially exploited for the production of the macrolide spiramycin which is used in human medicine as an antibacterial and anti-toxoplasmosis chemical. Its genome consists of a 8.3Mbp linear chromosome and a 89kb circular plasmid. The complete genome sequence reported here will enable us to investigate Streptomyces genome evolution and to discover new secondary metabolites with potential applications notably in human medicine.
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Pseudomonas fluorescens Pirates both Ferrioxamine and Ferricoelichelin Siderophores from Streptomyces ambofaciens.
Applied and Environmental Microbiology, 2015Co-Authors: Justine Galet, Pierre Leblond, Aurelie Deveau, Laurence Hotel, Pascale Frey-klett, Bertrand AigleAbstract:Iron is essential in many biological processes. However, its bioavailability is reduced in aerobic environments, such as soil. To overcome this limitation, microorganisms have developed different strategies, such as iron chelation by siderophores. Some bacteria have even gained the ability to detect and utilize xenosiderophores, i.e., siderophores produced by other organisms. We illustrate an example of such an interaction between two soil bacteria, Pseudomonas fluorescens strain BBc6R8 and Streptomyces ambofaciens ATCC 23877, which produce the siderophores pyoverdine and enantiopyochelin and the siderophores desferrioxamines B and E and coelichelin, respectively. During pairwise cultures on iron-limiting agar medium, no induction of siderophore synthesis by P. fluorescens BBc6R8 was observed in the presence of S. ambofaciens ATCC 23877. Cocultures with a Streptomyces mutant strain that produced either coelichelin or desferrioxamines, as well as culture in a medium supplemented with desferrioxamine B, resulted in the absence of pyoverdine production; however, culture with a double mutant deficient in desferrioxamines and coelichelin production did not. This strongly suggests that P. fluorescens BBbc6R8 utilizes the ferrioxamines and ferricoelichelin produced by S. ambofaciens as xenosiderophores and therefore no longer activates the production of its own siderophores. A screening of a library of P. fluorescens BBc6R8 mutants highlighted the involvement of the TonB-dependent receptor FoxA in this process: the expression of foxA and genes involved in the regulation of its biosynthesis was induced in the presence of S. ambofaciens. In a competitive environment, such as soil, siderophore piracy could well be one of the driving forces that determine the outcome of microbial competition.
Bernard Decaris - One of the best experts on this subject based on the ideXlab platform.
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genetic instability of whig gene during the aerial mycelium development of Streptomyces ambofaciens atcc23877 under different conditions of nitrogen limitations
Mutation Research, 2006Co-Authors: Magali Genay, Bernard Decaris, Sibel Catakli, Axelle Andrieux, Alexandra Kleinclauss, Annie DaryAbstract:In Streptomyces ambofaciens, white papillae that genetic instability events generate during aerial mycelium growth, give rise to Pig-pap mutants which are unable to sporulate and devoid of large genome rearrangement. Knowing that genetic and environmental factors can influence the number of papillae per colony, we investigated the effect of nutrient limitated conditions of growth on the formation of white papillae. We observed that under nitrogen limitation and, most particularly, under amino acid limitation, the number of papillae per colony dramatically increased. Most of the Pig-pap mutants deriving from such papillae displayed a mutation in the whiG gene, which encodes the sigma factor sigma(whiG) which is absolutely required for the sporulation process. In most cases, the mutation led to a loss of function. We showed that the Pig-pap mutants deriving from papillae appearing under usual growth conditions also frequently displayed null mutation of whiG too. As the whiG mutation ratio among the Pig-pap mutants isolated with or without nitrogen limited conditions did not change, the results described in this paper suggest that the production of papillae could constitute a response of S. ambofaciens to an amino acid limitation.
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Sigma factor WhiG and its regulation constitute a target of a mutational phenomenon occuring during aerial mycelium growth in Streptomyces ambofaciens ATCC23877
Research in Microbiology, 2005Co-Authors: Sibel Catakli, Bernard Decaris, Axelle Andrieux, Annie DaryAbstract:The genetic instability of Streptomyces ambofaciens affects the pigmentation of colonies and generates a variety of mutants the majority of which display large genome rearrangements. Among them, the Pig-pap mutants, which probably result from a mutational event occurring during aerial mycelium growth, display specific features, since they are unable to sporulate and do not harbor any large detectable genome rearrangements. To identify the mutational event causing their phenotype, three Pig-pap mutants originating from three independent mutational events were characterized. These mutants exhibited a whiG-like phenotype which was suppressed by the introduction of one copy of Streptomyces coelicolor whiG. Their own whiG gene was devoid of mutations and appeared to be transcribed at a level similar to that of the WT. However, whiH, the expression of which depends on sigma(WhiG), was not transcribed in any of the three Pig-pap mutants, suggesting that the sigma(WhiG) was absent or inactive. This suggests that in these Pig-pap mutants, the regulation of sigma(WhiG) might be affected. Finally, the introduction of S. coelicolor whiG in one of these Pig-pap mutants restored not only pigmentation and sporulation, but also the ability to once again form white papillae. Analyses of transgene whiG in these papillae revealed that it constitutes a mutational target during aerial mycelium formation when integrated into the genome of this Pig-pap mutant.
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differential and cross transcriptional control of duplicated genes encoding alternative sigma factors in Streptomyces ambofaciens
Journal of Bacteriology, 2004Co-Authors: Virginie Roth, Bertrand Aigle, Bernard Decaris, Thomas Wenner, Robert Bunet, Celine Fourrier, Pierre LeblondAbstract:The duplicated hasR and hasL genes of Streptomyces ambofaciens encode alternative sigma factors (named σBR and σBL) belonging to the σB general stress response family in Bacillus subtilis. The duplication appears to be the result of a recent event that occurred specifically in S. ambofaciens. The two genes are 98% identical, and their deduced protein products exhibit 97% identity at the amino acid level. In contrast with the coding sequences, their genetic environments and their transcriptional control are strongly divergent. While hasL is monocistronic, hasR is arranged in a polycistronic unit with two upstream open reading frames, arsR and prsR, that encode putative anti-anti-σ and anti-σ factors, respectively. Transcription of each has gene is initiated from two promoters. In each case, one promoter was shown to be developmentally controlled and to be similar to those recognized by the B. subtilis general stress response sigma factor σB. Expression from this type of promoter for each of the has genes dramatically increases during the course of growth in liquid or on solid media and following oxidative and osmotic stresses. Reverse transcription-PCR measurements indicate that hasR is 100 times more strongly expressed than hasL from the σB-like promoter. Transcription from the second promoter of each gene (located upstream of arsR in the case of the hasR locus) appears to be constitutive and weak. Quantitative transcriptional analysis in single and double has mutant strains revealed that σBR and σBL direct their own transcription as well as that of their duplicates. Only a slight sensitivity in response to oxidative conditions could be assigned to either single or double mutants, revealing the probable redundancy of the σ factors implied in stress response in Streptomyces.
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Functional Angucycline-Like Antibiotic Gene Cluster in the Terminal Inverted Repeats of the Streptomyces ambofaciens Linear Chromosome
Antimicrobial Agents and Chemotherapy, 2004Co-Authors: Xiuhua Pang, Bertrand Aigle, Bernard Decaris, Jean-luc Pernodet, Jean-michel Girardet, Sophie Mangenot, Pierre LeblondAbstract:Streptomyces ambofaciens has an 8-Mb linear chromosome ending in 200-kb terminal inverted repeats. Analysis of the F6 cosmid overlapping the terminal inverted repeats revealed a locus similar to type II polyketide synthase (PKS) gene clusters. Sequence analysis identified 26 open reading frames, including genes encoding the -ketoacyl synthase (KS), chain length factor (CLF), and acyl carrier protein (ACP) that make up the minimal PKS. These KS, CLF, and ACP subunits are highly homologous to minimal PKS subunits involved in the biosynthesis of angucycline antibiotics. The genes encoding the KS and ACP subunits are transcribed constitutively but show a remarkable increase in expression after entering transition phase. Five genes, including those encoding the minimal PKS, were replaced by resistance markers to generate single and double mutants (replacement in one and both terminal inverted repeats). Double mutants were unable to produce either diffusible orange pigment or antibacterial activity against Bacillus subtilis. Single mutants showed an intermediate phenotype, suggesting that each copy of the cluster was functional. Transformation of double mutants with a conjugative and integrative form of F6 partially restored both phenotypes. The pigmented and antibacterial compounds were shown to be two distinct molecules produced from the same biosynthetic pathway. High-pressure liquid chromatography analysis of culture extracts from wild-type and double mutants revealed a peak with an associated bioactivity that was absent from the mutants. Two additional genes encoding KS and CLF were present in the cluster. However, disruption of the second KS gene had no effect on either pigment or antibiotic production.
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spontaneous chromosome circularization and amplification of a new amplifiable unit of dna belonging to the terminal inverted repeats in Streptomyces ambofaciens atcc 23877
Archives of Microbiology, 2003Co-Authors: Sibel Catakli, Pierre Leblond, Bernard Decaris, Axelle Andrieux, Annie DaryAbstract:In Streptomyces, the linear chromosomal DNA is highly unstable and undergoes large rearrangements usually at the extremities. These rearrangements consist of the deletion of several hundred kilobases, often associated with the amplification of an adjacent sequence, AUD ( amplifiable unit of DNA). In Streptomyces ambofaciens, two amplifiable regions (AUD6 and AUD90), located approximately 600 kb and 1,200 kb from the right chromosomal end respectively, have been characterized. Here, the isolation and molecular characterization of a new S. ambofaciens mutant strain exhibiting a green-pigmented phenotype is described; the wild-type produces a gray pigment. In this mutant, both chromosome ends were deleted, which probably led to circularization of the chromosome. These deletions were associated with amplification of a sequence belonging to the chromosomal terminal inverted repeats (TIRs), which might constitute the new fragment generated by the chromosomal circularization.
Jean-luc Pernodet - One of the best experts on this subject based on the ideXlab platform.
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Draft Genome Sequence of Streptomyces sp. M1013, a Close Relative of Streptomyces ambofaciens and Streptomyces coelicolor
Genome Announcements, 2017Co-Authors: Drago Haas, Jean-luc Pernodet, Claude Gerbaud, Nevzat Sahin, Sylvie LautruAbstract:We report the draft genome sequence of Streptomyces sp. M1013, a strain isolated from the Medicago arborea rhizosphere in Izmir, Turkey. An average nucleotide identity (ANI) analysis reveals that this strain belongs to the same species as Streptomyces canus ATCC12647 and is closely related to Streptomyces ambofaciens and Streptomyces coelicolor.
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Complete genome sequence of Streptomyces ambofaciens ATCC 23877, the spiramycin producer
Journal of Biotechnology, 2015Co-Authors: Annabelle Thibessard, Bertrand Aigle, Jean-luc Pernodet, Sylvie Lautru, Drago Haas, Claude Gerbaud, Pierre LeblondAbstract:Streptomyces ambofaciens ATCC23877 is a soil bacterium industrially exploited for the production of the macrolide spiramycin which is used in human medicine as an antibacterial and anti-toxoplasmosis chemical. Its genome consists of a 8.3Mbp linear chromosome and a 89kb circular plasmid. The complete genome sequence reported here will enable us to investigate Streptomyces genome evolution and to discover new secondary metabolites with potential applications notably in human medicine.
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Genome mining of Streptomyces ambofaciens
Journal of Industrial Microbiology and Biotechnology, 2014Co-Authors: Bertrand Aigle, Pierre Leblond, Sylvie Lautru, Dieter Spiteller, Jeroen S. Dickschat, Gregory L. Challis, Jean-luc PernodetAbstract:Since the discovery of the streptomycin produced by Streptomyces griseus in the middle of the last century, members of this bacterial genus have been largely exploited for the production of secondary metabolites with wide uses in medicine and in agriculture. They have even been recognized as one of the most prolific producers of natural products among microorganisms. With the onset of the genomic era, it became evident that these microorganisms still represent a major source for the discovery of novel secondary metabolites. This was highlighted with the complete genome sequencing of Streptomyces coelicolor A3(2) which revealed an unexpected potential of this organism to synthesize natural products undetected until then by classical screening methods. Since then, analysis of sequenced genomes from numerous Streptomyces species has shown that a single species can carry more than 30 secondary metabolite gene clusters, reinforcing the idea that the biosynthetic potential of this bacterial genus is far from being fully exploited. This review highlights our knowledge on the potential of Streptomyces ambofaciens ATCC 23877 to synthesize natural products. This industrial strain was known for decades to only produce the drug spiramycin and another antibacterial compound, congocidine. Mining of its genome allowed the identification of 23 clusters potentially involved in the production of other secondary metabolites. Studies of some of these clusters resulted in the characterization of novel compounds and of previously known compounds but never characterized in this Streptomyces species. In addition, genome mining revealed that secondary metabolite gene clusters of phylogenetically closely related Streptomyces are mainly species-specific.
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Post-PKS Tailoring Steps of the Spiramycin Macrolactone Ring in Streptomyces ambofaciens.
Antimicrobial Agents and Chemotherapy, 2013Co-Authors: Hoang Chuong Nguyen, Jean-luc Pernodet, Emmanuelle Darbon, Robert Thai, Sylvie LautruAbstract:Spiramycins are clinically important 16-member macrolide antibiotics produced by Streptomyces ambofaciens. Biosynthetic studies have established that the earliest lactonic intermediate in spiramycin biosynthesis, the macrolactone platenolide I, is synthesized by a type I modular polyketide synthase (PKS). Platenolide I then undergoes a series of post-PKS tailoring reactions yielding the final products, spiramycins I, II, and III. We recently characterized the post-PKS glycosylation steps of spiramycin biosynthesis in S. ambofaciens. We showed that three glycosyltransferases, Srm5, Srm29, and Srm38, catalyze the successive attachment of the three carbohydrates mycaminose, forosamine, and mycarose, respectively, with the help of two auxiliary proteins, Srm6 and Srm28. However, the enzymes responsible for the other tailoring steps, namely, the C-19 methyl group oxidation, the C-9 keto group reduction, and the C-3 hydroxyl group acylation, as well as the timing of the post-PKS tailoring reactions, remained to be established. In this study, we show that Srm13, a cytochrome P450, catalyzes the oxidation of the C-19 methyl group into a formyl group and that Srm26 catalyzes the reduction of the C-9 keto group, and we propose a timeline for spiramycin-biosynthetic post-PKS tailoring reactions.
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Regulation of the biosynthesis of the macrolide antibiotic spiramycin in Streptomyces ambofaciens.
Journal of Bacteriology, 2010Co-Authors: Fatma Karray, Josette Gagnat, Emmanuelle Darbon, Hoang Chuong Nguyen, Jean-luc PernodetAbstract:Streptomyces ambofaciens synthesizes the macrolide antibiotic spiramycin. The biosynthetic gene cluster for spiramycin has been characterized for S. ambofaciens. In addition to the regulatory gene srmR (srm22), previously identified (M. Geistlich et al., Mol. Microbiol. 6:2019-2029, 1992), three putative regulatory genes had been identified by sequence analysis. Gene expression analysis and gene inactivation experiments showed that only one of these three genes, srm40, plays a major role in the regulation of spiramycin biosynthesis. The disruption of srm22 or srm40 eliminated spiramycin production while their overexpression increased spiramycin production. Expression analysis was performed by reverse transcription-PCR (RT-PCR) for all the genes of the cluster in the wild-type strain and in the srm22 (srmR) and srm40 deletion mutants. The results from the expression analysis, together with the ones from the complementation experiments, indicated that Srm22 is required for srm40 expression, Srm40 being a pathway-specific activator that controls most, if not all, of the spiramycin biosynthetic genes.
Bertrand Aigle - One of the best experts on this subject based on the ideXlab platform.
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Complete genome sequence of Streptomyces ambofaciens ATCC 23877, the spiramycin producer
Journal of Biotechnology, 2015Co-Authors: Annabelle Thibessard, Bertrand Aigle, Jean-luc Pernodet, Sylvie Lautru, Drago Haas, Claude Gerbaud, Pierre LeblondAbstract:Streptomyces ambofaciens ATCC23877 is a soil bacterium industrially exploited for the production of the macrolide spiramycin which is used in human medicine as an antibacterial and anti-toxoplasmosis chemical. Its genome consists of a 8.3Mbp linear chromosome and a 89kb circular plasmid. The complete genome sequence reported here will enable us to investigate Streptomyces genome evolution and to discover new secondary metabolites with potential applications notably in human medicine.
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Pseudomonas fluorescens Pirates both Ferrioxamine and Ferricoelichelin Siderophores from Streptomyces ambofaciens.
Applied and Environmental Microbiology, 2015Co-Authors: Justine Galet, Pierre Leblond, Aurelie Deveau, Laurence Hotel, Pascale Frey-klett, Bertrand AigleAbstract:Iron is essential in many biological processes. However, its bioavailability is reduced in aerobic environments, such as soil. To overcome this limitation, microorganisms have developed different strategies, such as iron chelation by siderophores. Some bacteria have even gained the ability to detect and utilize xenosiderophores, i.e., siderophores produced by other organisms. We illustrate an example of such an interaction between two soil bacteria, Pseudomonas fluorescens strain BBc6R8 and Streptomyces ambofaciens ATCC 23877, which produce the siderophores pyoverdine and enantiopyochelin and the siderophores desferrioxamines B and E and coelichelin, respectively. During pairwise cultures on iron-limiting agar medium, no induction of siderophore synthesis by P. fluorescens BBc6R8 was observed in the presence of S. ambofaciens ATCC 23877. Cocultures with a Streptomyces mutant strain that produced either coelichelin or desferrioxamines, as well as culture in a medium supplemented with desferrioxamine B, resulted in the absence of pyoverdine production; however, culture with a double mutant deficient in desferrioxamines and coelichelin production did not. This strongly suggests that P. fluorescens BBbc6R8 utilizes the ferrioxamines and ferricoelichelin produced by S. ambofaciens as xenosiderophores and therefore no longer activates the production of its own siderophores. A screening of a library of P. fluorescens BBc6R8 mutants highlighted the involvement of the TonB-dependent receptor FoxA in this process: the expression of foxA and genes involved in the regulation of its biosynthesis was induced in the presence of S. ambofaciens. In a competitive environment, such as soil, siderophore piracy could well be one of the driving forces that determine the outcome of microbial competition.
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siderophores from Streptomyces ambofaciens
2015Co-Authors: Justine Galet, Aurelie Deveau, Laurence Hotel, Pascale Freyklett, Bertrand AigleAbstract:8QLYHUVLWp GH /RUUDLQH ,QWHUDFWLRQV $UEUHV0LFURRUJDQLVPHV 80 5 13 9DQG°XYUHOqV1DQF\))UDQFH14 15 5XQQLQJ+HDG P. fluorescens SLUDWHV Streptomyces VLGHURSKRUHV 16 )227127(617 $GGUHVVFRUUHVSRQGHQFHWR%HUWUDQG$LJOH18 HPDLO EHUWUDQGDLJOH#XQLYORUUDLQHIU WHO ID[ 19 20 .H\ZRUGV21 [HQRVLGHURSKRUH Streptomyces ambofaciens Pseudomonas fluorescens LURQ22 FKHODWLRQ7RQ%GHSHQGHQWUHFHSWRU23 24 25 26 AEM Accepted Manuscript Posted Online 27 February 2015Appl. Environ. Microbiol. doi:10.1128/AEM.03520-14Copyright © 2015, American Society for Microbiology. All Rights Reserved.
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Genome mining of Streptomyces ambofaciens
Journal of Industrial Microbiology and Biotechnology, 2014Co-Authors: Bertrand Aigle, Pierre Leblond, Sylvie Lautru, Dieter Spiteller, Jeroen S. Dickschat, Gregory L. Challis, Jean-luc PernodetAbstract:Since the discovery of the streptomycin produced by Streptomyces griseus in the middle of the last century, members of this bacterial genus have been largely exploited for the production of secondary metabolites with wide uses in medicine and in agriculture. They have even been recognized as one of the most prolific producers of natural products among microorganisms. With the onset of the genomic era, it became evident that these microorganisms still represent a major source for the discovery of novel secondary metabolites. This was highlighted with the complete genome sequencing of Streptomyces coelicolor A3(2) which revealed an unexpected potential of this organism to synthesize natural products undetected until then by classical screening methods. Since then, analysis of sequenced genomes from numerous Streptomyces species has shown that a single species can carry more than 30 secondary metabolite gene clusters, reinforcing the idea that the biosynthetic potential of this bacterial genus is far from being fully exploited. This review highlights our knowledge on the potential of Streptomyces ambofaciens ATCC 23877 to synthesize natural products. This industrial strain was known for decades to only produce the drug spiramycin and another antibacterial compound, congocidine. Mining of its genome allowed the identification of 23 clusters potentially involved in the production of other secondary metabolites. Studies of some of these clusters resulted in the characterization of novel compounds and of previously known compounds but never characterized in this Streptomyces species. In addition, genome mining revealed that secondary metabolite gene clusters of phylogenetically closely related Streptomyces are mainly species-specific.
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Genome-guided Exploration of Streptomyces ambofaciens Secondary Metabolism
2011Co-Authors: Bertrand Aigle, Sylvie Lautru, Sarka Nezbedova, Robert Bunet, Christophe Corre, Amélie Garenaux, S. Huang, Luisa Laureti, Maria Vaz Mendez, H.c. NguyenAbstract:Members of the Streptomyces genus are among the most prolific microorganisms producing secondary metabolites with wide uses in medicine and in agriculture. Sequencing of the genome of the model Streptomyces, Streptomyces coelicolor, has highlighted an unexpected feature, i.e. that the potential of these organisms to synthesise secondary metabolites has been largely underestimated. They indeed possess many more gene clusters encoding natural product-like biosynthetic pathways than there are known natural products. Similar observations have since been made for other bacterial or fungal genomes. Thus, it became clear that microbial secondary metabolism had been seriously underestimated and that genome-based approaches were very promising for the search of new bioactive compounds. Here, we present an overview of the secondary metabolite biosynthetic potential of Streptomyces ambofaciens, a species known for decades as producer of the macrolide spiramycin and the pyrrolamide congocidine. Interestingly, genome analysis has revealed that despite of the close phylogenetic relatedness between S. coelicolor and S. ambofaciens, most of its secondary metabolite gene clusters are species-specific.
B Decaris - One of the best experts on this subject based on the ideXlab platform.
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Large genomic rearrangements of the unstable region in Streptomyces ambofaciens are associated with major changes in global gene expression.
Molecular Microbiology, 1993Co-Authors: A Dary, N Bourget, J M Simonet, P Kaiser, C J Thompson, B DecarisAbstract:Global gene expression is dramatically altered by genomic rearrangements in Streptomyces ambofaciens RP181110. Partial genome mapping of two derivatives of strain RP181110 (strains NSA205 and NSA228) revealed rearrangements located in the unstable region of the genome (deletion in strain NSA228; deletion and amplification in strain NSA205). Computerized comparisons of pulse-labelled proteins separated by two-dimensional electrophoresis have revealed numerous differences in gene expression among the three strains during both exponential and stationary phases of growth: 31 proteins were absent in both mutant strains, 16 were absent only in strain NSA228, 17 were absent only in strain NSA205 and 9 were found to be present or overexpressed in strain NSA205. Thus, in spite of the scarcity of genetic markers in the unstable region and its dispensability for growth under laboratory conditions, these results suggest that it includes genes which are actively expressed. Spontaneous gene amplifications, which occur frequently in this region of the chromosome, can further activate their expression.
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Stimulation of genetic instability in Streptomyces ambofaciens ATCC 23877 by antibiotics that interact with DNA gyrase
Journal of general microbiology, 1993Co-Authors: J.-n. Volff, J M Simonet, D. Vandewiele, B DecarisAbstract:In wild-type Streptomyces ambofaciens ATCC 23877, pigment-defective (Pig-) mutants arise at a frequency of about 0.5%; this genetic instability is related to genomic rearrangements such as deletions and/or amplifications of DNA sequences. On media containing oxolinic acid and novobiocin, which interact with the A and B subunits of DNA gyrase, respectively, the frequency of variants increased dramatically. The Pig- mutant frequency was increased to almost 100% on a medium containing oxolinic acid at a concentration allowing 55% survival. On solid medium containing either oxolinic acid or novobiocin at subinhibitory concentrations, most colonies exhibited a 'patchwork' phenotype, characterized by the presence of numerous Pig- sectors. Similar phenomena were not observed on media containing the transcriptional inhibitor rifampicin or the translational inhibitor streptomycin. Many of the Pig- mutants exhibited a pleiotropic phenotype and were affected in aerial mycelium formation, colony growth and/or prototrophy. Moreover, the same kinds of rearrangements (deletions and/or amplifications of DNA sequences) were found in both induced and spontaneous Pig- mutants. The results suggest either that DNA gyrase is directly involved in genetic instability or that an SOS-like system is implicated.
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Primary structure analysis of a duplicated region in the amplifiable AUD6 locus of Streptomyces ambofaciens DSM40697
FEMS Microbiology Letters, 1993Co-Authors: Martine Aubert, J M Simonet, E Weber, D Schneider, B DecarisAbstract:In Streptomyces ambofaciens, an amplifiable unit of DNA (AUD6) contains two homologous sequences, one located on the right extremity of the AUD (S1R), the other being internal (IHS). This paper presents the molecular analysis of this duplication. The nucleotide sequences are almost identical (95%) and each contains an ORF of about 330 codons, the two ORFs being nearly identical. The two hypothetical proteins, deduced from these sequences, show about 30% identity with different bacterial repressors. They also show a particularly strong similarity (90% identity between the full-length sequences) with hypothetical proteins of Streptomyces lividans 66 encoded by sequences also present on an amplifiable DNA region (AUD1).
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Amplification of a particular DNA sequence in Streptomyces ambofaciens RP181110 reversibly prevents spiramycin production.
Research in Microbiology, 1992Co-Authors: A Dary, N Bourget, N Girard, J M Simonet, B DecarisAbstract:Streptomyces ambofaciens RP181110 produces the macrolide antibiotic spiramycin. After treatment with ethidium bromide, 7 strains presenting an amplified sequence of DNA (ADS) were found in its progeny. These ADS were localized within the same amplifiable region of the RP181110 genome. It has been established that these amplified strains were non-producers (Spi-) and that the loss of one particular ADS was correlated with restoration of spiramycin production. Genome rearrangements such as deletions were detected on the same side of the amplifiable region in both amplified and deamplified strains.