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AbuSara NF, Piercey BM, Moore MA, Shaikh AA, Nothias LF, Srivastava SK, Cruz-Morales P, Dorrestein PC, Barona-Gómez F, Tahlan K. Comparative Genomics and Metabolomics Analyses of Clavulanic Acid-Producing Streptomyces Species Provides Insight Into Specialized Metabolism. Front Microbiol 2019; 10:2550. [PMID: 31787949 PMCID: PMC6856088 DOI: 10.3389/fmicb.2019.02550] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/22/2019] [Indexed: 01/13/2023] Open
Abstract
Clavulanic acid is a bacterial specialized metabolite, which inhibits certain serine β-lactamases, enzymes that inactivate β-lactam antibiotics to confer resistance. Due to this activity, clavulanic acid is widely used in combination with penicillin and cephalosporin (β-lactam) antibiotics to treat infections caused by β-lactamase-producing bacteria. Clavulanic acid is industrially produced by fermenting Streptomyces clavuligerus, as large-scale chemical synthesis is not commercially feasible. Other than S. clavuligerus, Streptomyces jumonjinensis and Streptomyces katsurahamanus also produce clavulanic acid along with cephamycin C, but information regarding their genome sequences is not available. In addition, the Streptomyces contain many biosynthetic gene clusters thought to be "cryptic," as the specialized metabolites produced by them are not known. Therefore, we sequenced the genomes of S. jumonjinensis and S. katsurahamanus, and examined their metabolomes using untargeted mass spectrometry along with S. clavuligerus for comparison. We analyzed the biosynthetic gene cluster content of the three species to correlate their biosynthetic capacities, by matching them with the specialized metabolites detected in the current study. It was recently reported that S. clavuligerus can produce the plant-associated metabolite naringenin, and we describe more examples of such specialized metabolites in extracts from the three Streptomyces species. Detailed comparisons of the biosynthetic gene clusters involved in clavulanic acid (and cephamycin C) production were also performed, and based on our analyses, we propose the core set of genes responsible for producing this medicinally important metabolite.
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Affiliation(s)
- Nader F. AbuSara
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Brandon M. Piercey
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Marcus A. Moore
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Arshad Ali Shaikh
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Louis-Félix Nothias
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
| | | | - Pablo Cruz-Morales
- Evolution of Metabolic Diversity Laboratory, Unidad de Genómica Avanzada (Langebio), Cinvestav-IPN, Irapuato, Mexico
| | - Pieter C. Dorrestein
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Francisco Barona-Gómez
- Evolution of Metabolic Diversity Laboratory, Unidad de Genómica Avanzada (Langebio), Cinvestav-IPN, Irapuato, Mexico
| | - Kapil Tahlan
- Department of Biology, Memorial University of Newfoundland, St. John’s, NL, Canada
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Fu J, Qin R, Zong G, Liu C, Kang N, Zhong C, Cao G. The CagRS Two-Component System Regulates Clavulanic Acid Metabolism via Multiple Pathways in Streptomyces clavuligerus F613-1. Front Microbiol 2019; 10:244. [PMID: 30837970 PMCID: PMC6382702 DOI: 10.3389/fmicb.2019.00244] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 01/29/2019] [Indexed: 11/21/2022] Open
Abstract
Streptomyces clavuligerus F613-1 produces a clinically important β-lactamase inhibitor, clavulanic acid (CA). Although the biosynthesis pathway of CA has essentially been elucidated, the global regulatory mechanisms of CA biosynthesis remain unclear. The paired genes cagS and cagR, which are annotated, respectively, as orf22 and orf23 in S. clavuligerus ATCC 27064, encode a bacterial two-component regulatory system (TCS) and were found next to the CA biosynthetic gene cluster of S. clavuligerus F613-1. To further elucidate the regulatory mechanism of CA biosynthesis, the CagRS TCS was deleted from S. clavuligerus F613-1. Deletion of cagRS resulted in decreased production of CA, but the strain phenotype was not otherwise affected. Both transcriptome and ChIP-seq data revealed that, in addition to CA biosynthesis, the CagRS TCS mainly regulates genes involved in primary metabolism, such as glyceraldehyde 3-phosphate (G3P) metabolism and arginine biosynthesis. Notably, both G3P and arginine are precursors of CA. Electrophoretic mobility shift assays demonstrated that the response regulator CagR could bind to the intergenic regions of argG, argC, oat1, oat2, ceaS1, and claR in vitro, suggesting that CagR can directly regulate genes involved in arginine and CA biosynthesis. This study indicated that CagRS is a pleiotropic regulator that can directly affect the biosynthesis of CA and indirectly affect CA production by regulating the metabolism of arginine and G3P. Our findings provide new insights into the regulation of CA biosynthetic pathways and provide an innovative approach for future metabolic engineering efforts for CA production in S. clavuligerus.
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Affiliation(s)
- Jiafang Fu
- Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan, China
| | - Ronghuo Qin
- Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan, China
| | - Gongli Zong
- Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan, China
| | - Cheng Liu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, China
| | - Ni Kang
- Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan, China
| | - Chuanqing Zhong
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, China
| | - Guangxiang Cao
- Shandong Medicinal Biotechnology Center, Shandong Academy of Medical Sciences, Jinan, China
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Ünsaldı E, Kurt-Kızıldoğan A, Voigt B, Becher D, Özcengiz G. Proteome-wide alterations in an industrial clavulanic acid producing strain of Streptomyces clavuligerus. Synth Syst Biotechnol 2016; 2:39-48. [PMID: 29062960 PMCID: PMC5625738 DOI: 10.1016/j.synbio.2016.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 10/17/2016] [Accepted: 10/23/2016] [Indexed: 11/26/2022] Open
Abstract
The usefulness of genetic/metabolic engineering for further improvement of industrial strains is subject of discussion because of the general lack of knowledge on genetic alterations introduced by iterative cycles of random mutagenesis in such strains. An industrial clavulanic acid (CA)-overproducer Streptomyces clavuligerus DEPA was assessed to understand proteome-wide changes that have occurred in a local industrial CA overproducer developed through succesive mutagenesis programs. The proteins that could be identified corresponded to 33 distinct ORFs for underrepresented ones and 60 ORFs for overrepresented ones. Three CA biosynthetic enzymes were overrepresented in S. clavuligerus DEPA; carboxyethylarginine synthase (Ceas2), clavaldehyde dehydrogenase (Car) and carboxyethyl-arginine beta-lactam-synthase (Bls2) whereas the enzymes of two other secondary metabolites were underrepresented along with two important global regulators [two-component system (TCS) response regulator (SCLAV_2102) and TetR-family transcriptional regulator (SCLAV_3146)] that might be related with CA production and/or differentiation. γ-butyrolactone biosynthetic protein AvaA2 was 2.6 fold underrepresented in S. clavuligerus DEPA. The levels of two glycolytic enzymes, 2,3-bisphosphoglycerate-dependent phosphoglycerate mutase and phosophoglycerate kinase were found decreased while those of dihydrolipoyl dehydrogenase (E3) and isocitrate dehydrogenase, with two isoforms were found as significantly increased. A decrease of amino acid metabolism, methionine biosynthesis in particular, as well as S-adenosylmethionine synthetase appeared as one of the prominent mechanisms of success of S. clavuligerus DEPA strain as a prolific producer of CA. The levels of two enzymes of shikimate pathway that leads to the production of aromatic amino acids and aromatic secondary metabolites were also underrepresented. Some of the overrepresented stress proteins in S. clavuligerus DEPA included polynucleotide phosphorylase/polyadenylase (PNPase), ATP-dependent DNA helicase, two isoforms of an anti-sigma factor and thioredoxin reductase. Downregulation of important proteins of cell wall synthesis and division was recorded and a protein with β-lactamase domain (SCLAV_p1007) appeared in 12 isoforms, 5 of which were drastically overrepresented in DEPA strain. These results described herein provide useful information for rational engineering to improve CA production in Streptomyces clavuligerus.
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Affiliation(s)
- Eser Ünsaldı
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey
| | - Aslıhan Kurt-Kızıldoğan
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey.,Department of Agricultural Biotechnology, Ondokuz Mayıs University, 55139, Samsun, Turkey
| | - Birgit Voigt
- Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald, D-17487, Greifswald, Germany
| | - Dörte Becher
- Institute of Microbiology, Ernst-Moritz-Arndt-University of Greifswald, D-17487, Greifswald, Germany
| | - Gülay Özcengiz
- Department of Biological Sciences, Middle East Technical University, 06800, Ankara, Turkey
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Leite CA, Cavallieri AP, Araujo MLGC. Enhancing effect of lysine combined with other compounds on cephamycin C production in Streptomyces clavuligerus. BMC Microbiol 2013; 13:296. [PMID: 24359569 PMCID: PMC3880171 DOI: 10.1186/1471-2180-13-296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lysine plays an important role in Streptomyces clavuligerus metabolism; it takes part in its catabolism, via cadaverine, and in its secondary metabolism, in which lysine is converted via 1-piperideine-6-carboxylate to alpha-aminoadipic acid, a beta-lactam antibiotic precursor. The role of lysine as an enhancer of cephamycin C production, when added to production medium at concentrations above 50 mmol l(-1), has already been reported in the literature, with some studies attributing a positive influence to multifunctional diamines, among other compounds. However, there is a lack of research on the combined effect of these compounds on antibiotic production. RESULTS Results from experimental design-based tests were used to conduct response surface-based optimization studies in order to investigate the synergistic effect of combining lysine with cadaverine, putrescine, 1,3-diaminopropane, or alpha-aminoadipic acid on cephamycin C volumetric production. Lysine combined with cadaverine influenced production positively, but only at low lysine concentrations. On the whole, higher putrescine concentrations (0.4 g l(-1)) affected negatively cephamycin C volumetric production. In comparison to culture media containing only lysine as additive, combinations of this amino acid with alpha-aminoadipic acid or 1,3-diaminopropane increased cephamycin C production by more than 100%. CONCLUSION This study demonstrated that different combinations of lysine with diamines or lysine with alpha-aminoadipic acid engender significant differences with respect to antibiotic volumetric production, with emphasis on the benefits observed for lysine combined with alpha-aminoadipic acid or 1,3-diaminopropane. This increase is explained by mathematical models and demonstrated by means of bioreactor cultivations. Moreover, it is consistent with the positive influence of these compounds on lysine conversion to alpha-aminoadipic acid, a limiting step in cephamycin C production.
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Affiliation(s)
- Carla A Leite
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
| | - André P Cavallieri
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
| | - Maria L G C Araujo
- Department of Biochemistry and Technological Chemistry, UNESP - São Paulo State University, Institute of Chemistry, 14800-900 Araraquara, SP, Brazil
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Paradkar A. Clavulanic acid production by Streptomyces clavuligerus: biogenesis, regulation and strain improvement. J Antibiot (Tokyo) 2013; 66:411-20. [DOI: 10.1038/ja.2013.26] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/25/2013] [Accepted: 03/11/2013] [Indexed: 11/09/2022]
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Kwong T, Tahlan K, Anders CL, Jensen SE. Carboxyethylarginine synthase genes show complex cross-regulation in Streptomyces clavuligerus. Appl Environ Microbiol 2013; 79:240-9. [PMID: 23104404 DOI: 10.1128/AEM.02600-12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Carboxyethylarginine synthase is the first dedicated enzyme of clavam biosynthesis in Streptomyces clavuligerus and is present in two isoforms encoded by two separate genes. When grown on a liquid soy medium, strains with ceaS1 deleted showed only a mild reduction of clavam biosynthesis, while disruption of ceaS2 abolished all clavam biosynthesis. Creation of an in-frame ceaS2 deletion mutant to avoid polarity did not restore clavam production, nor did creation of a site-directed mutant altered only in a single amino acid residue important for activity. Reverse transcriptase PCR analyses of these mutants indicated that the failure to produce clavam metabolites could be traced to reduced or abolished transcription of ceaS1 in the ceaS2 mutants, despite the location of ceaS1 on a replicon completely separate from that of ceaS2. Western analyses further showed that the CeaS1 protein (as well as the CeaS2 protein) was absent from the ceaS2 mutants. Complementation experiments were able to restore clavam production partially, but only by virtue of restoring CeaS2 production. CeaS1 was still absent from the complemented strains. While this dependence of CeaS1 production on the expression of ceaS2 from its native chromosomal location was seen in all of the ceaS2 mutants, the effect was limited to growth in liquid medium. When the same mutants were grown on solid soy medium, clavam production was restored and CeaS1 was produced, albeit at low levels compared to the wild type.
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Abstract
Abstract
Naturally occurring clavam metabolites include the valuable β-lactamase inhibitor, clavulanic acid, as well as stereochemical variants with side-chain modifications, called the 5S clavams. Because of the clinical importance of clavulanic acid, most studies of clavam biosynthesis are based on the industrial producer species Streptomyces clavuligerus. Well-characterized early steps in clavam biosynthesis are outlined, and less well understood late steps in 5S clavam biosynthesis are proposed. The complex genetic organization of the clavam biosynthetic genes in S. clavuligerus is described and, where possible, comparisons with other producer species are presented.
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Goomeshi Nobary S, Jensen SE. A comparison of the clavam biosynthetic gene clusters in Streptomyces antibioticus Tü1718 and Streptomyces clavuligerus. Can J Microbiol 2012; 58:413-25. [PMID: 22435762 DOI: 10.1139/w2012-012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The production of clavam metabolites has been studied previously in Streptomyces clavuligerus , a species that produces clavulanic acid as well as 4 other clavam compounds, but the late steps of the pathway leading to the specific end products are unclear. The present study compared the clavam biosynthetic gene cluster in Streptomyces antibioticus , chosen because it produces only 2 clavam metabolites and no clavulanic acid, with that of S. clavuligerus. A cosmid library of S. antibioticus genomic DNA was screened with a clavaminate synthase-specific probe based on the corresponding genes from S. clavuligerus, and 1 of the hybridizing cosmids was sequenced in full. A clavam gene cluster was identified that shows similarities to that of S. clavuligerus but also contains a number of novel genes. Knock-out mutation of the clavaminate synthase gene abolished clavam production in S. antibioticus, confirming the identity of the gene cluster. Knock-out mutation of a novel gene encoding an apparent oxidoreductase also abolished clavam production. A potential clavam biosynthetic pathway consistent with the genes in the cluster and the metabolites produced by S. antibioticus, and correspondingly different from that of S. clavuligerus, is proposed.
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Affiliation(s)
- Sarah Goomeshi Nobary
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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Song JY, Jensen SE, Lee KJ. Clavulanic acid biosynthesis and genetic manipulation for its overproduction. Appl Microbiol Biotechnol 2010; 88:659-69. [DOI: 10.1007/s00253-010-2801-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 12/27/2022]
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Zelyas NJ, Cai H, Kwong T, Jensen SE. Alanylclavam biosynthetic genes are clustered together with one group of clavulanic acid biosynthetic genes in Streptomyces clavuligerus. J Bacteriol 2008; 190:7957-65. [PMID: 18931110 DOI: 10.1128/JB.00698-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptomyces clavuligerus produces at least five different clavam metabolites, including clavulanic acid and the methionine antimetabolite, alanylclavam. In vitro transposon mutagenesis was used to analyze a 13-kb region upstream of the known paralogue gene cluster. The paralogue cluster includes one group of clavulanic acid biosynthetic genes in S. clavuligerus. Twelve open reading frames (ORFs) were found in this area, and mutants were generated in each using either in vitro transposon or PCR-targeted mutagenesis. Mutants with defects in any of the genes orfA, orfB, orfC, or orfD were unable to produce alanylclavam but could produce all of the other clavams, including clavulanic acid. orfA encodes a predicted hydroxymethyltransferase, orfB encodes a YjgF/YER057c/UK114-family regulatory protein, orfC encodes an aminotransferase, and orfD encodes a dehydratase. All of these types of proteins are normally involved in amino acid metabolism. Mutants in orfC or orfD also accumulated a novel clavam metabolite instead of alanylclavam, and a complemented orfC mutant was able to produce trace amounts of alanylclavam while still producing the novel clavam. Mass spectrometric analyses, together with consideration of the enzymes involved in its production, led to tentative identification of the novel clavam as 8-OH-alanylclavam, an intermediate in the proposed alanylclavam biosynthetic pathway.
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Tahlan K, Anders C, Wong A, Mosher RH, Beatty PH, Brumlik MJ, Griffin A, Hughes C, Griffin J, Barton B, Jensen SE. 5S clavam biosynthetic genes are located in both the clavam and paralog gene clusters in Streptomyces clavuligerus. ACTA ACUST UNITED AC 2007; 14:131-42. [PMID: 17317567 DOI: 10.1016/j.chembiol.2006.11.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 09/22/2006] [Accepted: 11/13/2006] [Indexed: 10/23/2022]
Abstract
The Streptomyces clavuligerus clavam gene cluster was examined to identify genes specifically involved in 5S clavam biosynthesis. A reduction/loss of 5S clavam production was seen in cvm2 and cvm5 gene mutants, and a clavam metabolite not previously observed, 2-carboxymethylideneclavam, accumulated in the cvm5 mutant. Disruption of additional genes from the region of the clavam cluster did not have any effect on 5S clavam production. Examination of the paralog gene cluster region for 5S clavam biosynthetic genes led to the identification of cvm6P and cvm7P, which encode a putative aminotransferase and a transcriptional regulator, respectively. Mutants defective in cvm6P and cvm7P were completely blocked in 5S clavam but not clavulanic acid production. The loss of 5S clavam production in cvm7P mutants suggests that this gene encodes a transcriptional regulator specific for 5S clavam metabolite biosynthesis.
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Affiliation(s)
- Kapil Tahlan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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Abstract
Daptomycin (Cubicin) is a lipopeptide antibiotic approved in the USA in 2003 for the treatment of skin and skin structure infections caused by Gram-positive pathogens. It is a member of the 10-membered cyclic lipopeptide family of antibiotics that includes A54145, calcium-dependent antibiotic (CDA), amphomycin, friulimicin, laspartomycin, and others. This review highlights research on this class of antibiotics from 1953 to 2005, focusing on more recent studies with particular emphasis on the interplay between structural features and antibacterial activities; chemical modifications to improve activity; the genetic organization and biosynthesis of lipopeptides; and the genetic engineering of the daptomycin biosynthetic pathway to produce novel derivatives for further chemical modification to develop candidates for clinical evaluation.
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Arulanantham H, Kershaw NJ, Hewitson KS, Hughes CE, Thirkettle JE, Schofield CJ. ORF17 from the clavulanic acid biosynthesis gene cluster catalyzes the ATP-dependent formation of N-glycyl-clavaminic acid. J Biol Chem 2005; 281:279-87. [PMID: 16251194 DOI: 10.1074/jbc.m507711200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
(3R,5R)-Clavulanic acid, a clinically used inhibitor of serine beta-lactamases, is produced by fermentation of Streptomyces clavuligerus. The early steps in clavulanic acid biosynthesis leading to the bicyclic beta-lactam intermediate (3S,5S)-clavaminic acid have been defined. However, the mechanism by which (3S,5S)-clavaminic acid is converted to the penultimate intermediate (3R,5R)-clavaldehyde is unclear. Disruption of orf15 or orf16, of the clavulanic acid biosynthesis gene cluster, blocks clavulanic acid production and leads to the accumulation of N-acetyl-glycyl-clavaminic acid and N-glycyl-clavaminic acid, suggesting that these compounds are intermediates in the pathway. Two alternative start codons have been proposed for orf17 to encode for two possible polypeptides, one of which has 92 N-terminal residues less then the other. The shorter version of orf17 was successfully expressed in Escherichia coli and purified as a monomeric protein. Sequence analyses predicting the ORF17 protein to be a member of the ATP-grasp fold superfamily were supported by soft ionization mass spectrometric analyses that demonstrated binding of ATP to the ORF17 protein. Semisynthetic clavaminic acid, prepared by in vitro reconstitution of the biosynthetic pathway from the synthetically accessible intermediate proclavaminic acid, was shown by mass spectrometric analyses to be converted to N-glycyl-clavaminic acid in the presence of ORF17, ATP, and glycine. Under the same conditions N-acetyl-glycine and clavaminic acid were not converted to N-acetyl-glycyl-clavaminic acid. The specificity of ORF17 as an N-glycyl-clavaminic acid synthetase, together with the reported accumulation of N-glycyl-clavaminic acid in orf15 and orf16 disruption mutants, suggested that N-glycyl-clavaminic acid is an intermediate in clavulanic acid biosynthesis.
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Affiliation(s)
- Haren Arulanantham
- Department of Chemistry and The Oxford Centre for Molecular Sciences, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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Abstract
In Streptomyces clavuligerus, three groups of genes are known to be involved in the biosynthesis of the clavam metabolites. Since antibiotic biosynthetic genes are invariably clustered on the chromosome in prokaryotes, chromosome walking was undertaken in an attempt to show that the three groups of clavam genes would resolve into a single super-cluster when analyzed at larger scale. However, no evidence of linkage between the three groups was obtained. Furthermore, Southern analysis of macro-restriction fragments of genomic DNA separated by pulsed-field gel electrophoresis also indicated that the three groups of genes are not linked. Despite the structural and biosynthetic relatedness of the clavam metabolites, our results suggest that the genes involved in their production lie in three unlinked gene clusters. We believe that this represents the first instance in bacteria of genes involved in the biosynthesis of a single family of antibiotics sharing a common biosynthetic pathway and yet residing in three separate locations on the chromosome.
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Affiliation(s)
- Kapil Tahlan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.
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Bignell DRD, Tahlan K, Colvin KR, Jensen SE, Leskiw BK. Expression of ccaR, encoding the positive activator of cephamycin C and clavulanic acid production in Streptomyces clavuligerus, is dependent on bldG. Antimicrob Agents Chemother 2005; 49:1529-41. [PMID: 15793135 PMCID: PMC1068620 DOI: 10.1128/aac.49.4.1529-1541.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Streptomyces coelicolor, bldG encodes a putative anti-anti-sigma factor that regulates both aerial hypha formation and antibiotic production, and a downstream transcriptionally linked open reading frame (orf3) encodes a putative anti-sigma factor protein. A cloned DNA fragment from Streptomyces clavuligerus contained an open reading frame that encoded a protein showing 92% identity to the S. coelicolor BldG protein and 91% identity to the BldG ortholog in Streptomyces avermitilis. Sequencing of the region downstream of bldG in S. clavuligerus revealed the presence of an open reading frame encoding a protein showing 72 and 69% identity to the ORF3 proteins in S. coelicolor and S. avermitilis, respectively. Northern analysis indicated that, as in S. coelicolor, the S. clavuligerus bldG gene is expressed as both a monocistronic and a polycistronic transcript, the latter including the downstream orf3 gene. High-resolution S1 nuclease mapping of S. clavuligerus bldG transcripts revealed the presence of three bldG-specific promoters, and analysis of expression of a bldGp-egfp reporter indicated that the bldG promoter is active at various stages of development and in both substrate and aerial hyphae. A bldG null mutant was defective in both morphological differentiation and in the production of secondary metabolites, such as cephamycin C, clavulanic acid, and the 5S clavams. This inability to produce cephamycin C and clavulanic acid was due to the absence of the CcaR transcriptional regulator, which controls the expression of biosynthetic genes for both secondary metabolites as well as the expression of a second regulator of clavulanic acid biosynthesis, ClaR. This makes bldG the first regulatory protein identified in S. clavuligerus that functions upstream of CcaR and ClaR in a regulatory cascade to control secondary metabolite production.
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Affiliation(s)
- Dawn R D Bignell
- Department of Biological Sciences, CW405 Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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Tahlan K, Anders C, Jensen SE. The paralogous pairs of genes involved in clavulanic acid and clavam metabolite biosynthesis are differently regulated in Streptomyces clavuligerus. J Bacteriol 2004; 186:6286-97. [PMID: 15342599 PMCID: PMC515150 DOI: 10.1128/jb.186.18.6286-6297.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Carboxyethylarginine synthase, encoded by the paralogous ceaS1 and ceaS2 genes, catalyzes the first reaction in the shared biosynthetic pathway leading to clavulanic acid and the other clavam metabolites in Streptomyces clavuligerus. The nutritional regulation of ceaS1 and ceaS2 expression was analyzed by reverse transcriptase PCR and by the use of the enhanced green fluorescent protein-encoding gene (egfp) as a reporter. ceaS1 was transcribed in complex soy medium only, whereas ceaS2 was transcribed in both soy and defined starch-asparagine (SA) media. The transcriptional start points of the two genes were also mapped to a C residue 98 bp upstream of ceaS1 and a G residue 51 bp upstream of the ceaS2 start codon by S1 nuclease protection and primer extension analyses. Furthermore, transcriptional mapping of the genes encoding the beta-lactam synthetase (bls1) and proclavaminate amidinohydrolase (pah1) isoenzymes from the paralogue gene cluster indicated that a single polycistronic transcript of approximately 4.9 kb includes ceaS1, bls1, and pah1. The expression of ceaS1 and ceaS2 in a mutant strain defective in the regulatory protein CcaR was also examined. ceaS1 transcription was not affected in the ccaR mutant, whereas that of ceaS2 was greatly reduced compared to the wild-type strain. Overall, our results suggest that different mechanisms are involved in regulating the expression of ceaS1 and ceaS2, and presumably also of other paralogous genes that encode proteins involved in the early stages of clavulanic acid and clavam metabolite biosynthesis.
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Affiliation(s)
- Kapil Tahlan
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9.
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Tahlan K, Park HU, Wong A, Beatty PH, Jensen SE. Two sets of paralogous genes encode the enzymes involved in the early stages of clavulanic acid and clavam metabolite biosynthesis in Streptomyces clavuligerus. Antimicrob Agents Chemother 2004; 48:930-9. [PMID: 14982786 PMCID: PMC353097 DOI: 10.1128/aac.48.3.930-939.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recently, a second copy of a gene encoding proclavaminate amidinohydrolase (pah1), an enzyme involved in the early stages of clavulanic acid and clavam metabolite biosynthesis in Streptomyces clavuligerus, was identified and isolated. Using Southern analysis, we have now isolated second copies of the genes encoding the carboxyethylarginine synthase (ceaS) and beta-lactam synthetase (bls) enzymes. These new paralogues are given the gene designations ceaS1 and bls1 and are located immediately upstream of pah1 on the chromosome. Furthermore, sequence analysis of the region downstream of pah1 revealed a second copy of a gene encoding ornithine acetyltransferase (oat1), thus indicating the presence of a cluster of paralogue genes. ceaS1, bls1, and oat1 display 73, 60, and 63% identities, respectively, at the nucleotide level to the original ceaS2, bls2, and oat2 genes from the clavulanic acid gene cluster. Single mutants defective in ceaS1, bls1, or oat1 were prepared and characterized and were found to be affected to variable degrees in their ability to produce clavulanic acid and clavam metabolites. Double mutants defective in both copies of the genes were also prepared and tested. The ceaS1/ceaS2 and the bls1/bls2 mutant strains were completely blocked in clavulanic acid and clavam metabolite biosynthesis. On the other hand, oat1/oat2 double mutants still produced some clavulanic acid and clavam metabolites. This may be attributed to the presence of the argJ gene in S. clavuligerus, which encodes yet another ornithine acetyltransferase enzyme that may be able to compensate for the lack of OAT1 and -2 in the double mutants.
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Affiliation(s)
- Kapil Tahlan
- Department of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Canada.
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