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Comparative diversity of microbiomes and Resistomes in beef feedlots, downstream environments and urban sewage influent. BMC Microbiol 2019; 19:197. [PMID: 31455230 PMCID: PMC6712873 DOI: 10.1186/s12866-019-1548-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 07/19/2019] [Indexed: 01/24/2023] Open
Abstract
Background Comparative knowledge of microbiomes and resistomes across environmental interfaces between animal production systems and urban settings is lacking. In this study, we executed a comparative analysis of the microbiota and resistomes of metagenomes from cattle feces, catch basin water, manured agricultural soil and urban sewage. Results Metagenomic DNA from composite fecal samples (FC; n = 12) collected from penned cattle at four feedlots in Alberta, Canada, along with water from adjacent catchment basins (CB; n = 13), soil (n = 4) from fields in the vicinity of one of the feedlots and urban sewage influent (SI; n = 6) from two municipalities were subjected to Illumina HiSeq2000 sequencing. Firmicutes exhibited the highest prevalence (40%) in FC, whereas Proteobacteria were most abundant in CB (64%), soil (60%) and SI (83%). Among sample types, SI had the highest diversity of antimicrobial resistance (AMR), and metal and biocide resistance (MBR) classes (13 & 15) followed by FC (10 & 8), CB (8 & 4), and soil (6 & 1). The highest antimicrobial resistant (AMR) gene (ARG) abundance was harboured by FC, whereas soil samples had a very small, but unique resistome which did not overlap with FC & CB resistomes. In the beef production system, tetracycline resistance predominated followed by macrolide resistance. The SI resistome harboured β-lactam, macrolide, tetracycline, aminoglycoside, fluoroquinolone and fosfomycin resistance determinants. Metal and biocide resistance accounted for 26% of the SI resistome with a predominance of mercury resistance. Conclusions This study demonstrates an increasing divergence in the nature of the microbiome and resistome as the distance from the feedlot increases. Consistent with antimicrobial use, tetracycline and macrolide resistance genes were predominant in the beef production system. One of the feedlots contributed both conventional (raised with antibiotics) and natural (raised without antibiotics) pens samples. Although natural pen samples exhibited a microbiota composition that was similar to samples from conventional pens, their resistome was less complex. Similarly, the SI resistome was indicative of drug classes used in humans and the greater abundance of mercury resistance may be associated with contamination of municipal water with household and industrial products. Electronic supplementary material The online version of this article (10.1186/s12866-019-1548-x) contains supplementary material, which is available to authorized users.
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Binda E, Cappelletti P, Marinelli F, Marcone GL. Specificity of Induction of Glycopeptide Antibiotic Resistance in the Producing Actinomycetes. Antibiotics (Basel) 2018; 7:antibiotics7020036. [PMID: 29693566 PMCID: PMC6022977 DOI: 10.3390/antibiotics7020036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/19/2018] [Accepted: 04/20/2018] [Indexed: 12/21/2022] Open
Abstract
Glycopeptide antibiotics are drugs of last resort for treating severe infections caused by Gram-positive pathogens. It is widely believed that glycopeptide-resistance determinants (van genes) are ultimately derived from the producing actinomycetes. We hereby investigated the relationship between the antimicrobial activity of vancomycin and teicoplanins and their differential ability to induce van gene expression in Actinoplanes teichomyceticus—the producer of teicoplanin—and Nonomuraea gerenzanensis—the producer of the teicoplanin-like A40926. As a control, we used the well-characterized resistance model Streptomyces coelicolor. The enzyme activities of a cytoplasmic-soluble d,d-dipeptidase and of a membrane-associated d,d-carboxypeptidase (corresponding to VanX and VanY respectively) involved in resistant cell wall remodeling were measured in the actinomycetes grown in the presence or absence of subinhibitory concentrations of vancomycin, teicoplanin, and A40926. Results indicated that actinomycetes possess diverse self-resistance mechanisms, and that each of them responds differently to glycopeptide induction. Gene swapping among teicoplanins-producing actinomycetes indicated that cross-talking is possible and provides useful information for predicting the evolution of future resistance gene combinations emerging in pathogens.
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Affiliation(s)
- Elisa Binda
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
- The Protein Factory Research Center, Politecnico di Milano and University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
| | - Pamela Cappelletti
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
- The Protein Factory Research Center, Politecnico di Milano and University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
| | - Flavia Marinelli
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
- The Protein Factory Research Center, Politecnico di Milano and University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
| | - Giorgia Letizia Marcone
- Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
- The Protein Factory Research Center, Politecnico di Milano and University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.
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Binda E, Marinelli F, Marcone GL. Old and New Glycopeptide Antibiotics: Action and Resistance. Antibiotics (Basel) 2014; 3:572-94. [PMID: 27025757 PMCID: PMC4790382 DOI: 10.3390/antibiotics3040572] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 12/05/2022] Open
Abstract
Glycopeptides are considered antibiotics of last resort for the treatment of life-threatening infections caused by relevant Gram-positive human pathogens, such as Staphylococcus aureus, Enterococcus spp. and Clostridium difficile. The emergence of glycopeptide-resistant clinical isolates, first among enterococci and then in staphylococci, has prompted research for second generation glycopeptides and a flurry of activity aimed at understanding resistance mechanisms and their evolution. Glycopeptides are glycosylated non-ribosomal peptides produced by a diverse group of soil actinomycetes. They target Gram-positive bacteria by binding to the acyl-d-alanyl-d-alanine (d-Ala-d-Ala) terminus of the growing peptidoglycan on the outer surface of the cytoplasmatic membrane. Glycopeptide-resistant organisms avoid such a fate by replacing the d-Ala-d-Ala terminus with d-alanyl-d-lactate (d-Ala-d-Lac) or d-alanyl-d-serine (d-Ala-d-Ser), thus markedly reducing antibiotic affinity for the cellular target. Resistance has manifested itself in enterococci and staphylococci largely through the expression of genes (named van) encoding proteins that reprogram cell wall biosynthesis and, thus, evade the action of the antibiotic. These resistance mechanisms were most likely co-opted from the glycopeptide producing actinomycetes, which use them to avoid suicide during antibiotic production, rather than being orchestrated by pathogen bacteria upon continued treatment. van-like gene clusters, similar to those described in enterococci, were in fact identified in many glycopeptide-producing actinomycetes, such as Actinoplanes teichomyceticus, which produces teicoplanin, and Streptomyces toyocaensis, which produces the A47934 glycopeptide. In this paper, we describe the natural and semi-synthetic glycopeptide antibiotics currently used as last resort drugs for Gram-positive infections and compare the van gene-based strategies of glycopeptide resistance among the pathogens and the producing actinomycetes. Particular attention is given to the strategy of immunity recently described in Nonomuraea sp. ATCC 39727. Nonomuraea sp. ATCC 39727 is the producer of A40926, which is the natural precursor of the second generation semi-synthetic glycopeptide dalbavancin, very recently approved for acute bacterial skin and skin structure infections. A thorough understanding of glycopeptide immunity in this producing microorganism may be particularly relevant to predict and eventually control the evolution of resistance that might arise following introduction of dalbavancin and other second generation glycopeptides into clinics.
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Affiliation(s)
- Elisa Binda
- Department of Biotechnology and Life Sciences, University of Insubria, Varese 20100, Italy.
- The Protein Factory, Interuniversity Centre Politecnico di Milano, ICRM CNR Milano and University of Insubria, Milan 21100, Italy.
| | - Flavia Marinelli
- Department of Biotechnology and Life Sciences, University of Insubria, Varese 20100, Italy.
- The Protein Factory, Interuniversity Centre Politecnico di Milano, ICRM CNR Milano and University of Insubria, Milan 21100, Italy.
| | - Giorgia Letizia Marcone
- Department of Biotechnology and Life Sciences, University of Insubria, Varese 20100, Italy.
- The Protein Factory, Interuniversity Centre Politecnico di Milano, ICRM CNR Milano and University of Insubria, Milan 21100, Italy.
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Relationship between glycopeptide production and resistance in the actinomycete Nonomuraea sp. ATCC 39727. Antimicrob Agents Chemother 2014; 58:5191-201. [PMID: 24957828 DOI: 10.1128/aac.02626-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycopeptides and β-lactams inhibit bacterial peptidoglycan synthesis in Gram-positive bacteria; resistance to these antibiotics is studied intensively in enterococci and staphylococci because of their relevance to infectious disease. Much less is known about antibiotic resistance in glycopeptide-producing actinomycetes that are likely to represent the evolutionary source of resistance determinants found in bacterial pathogens. Nonomuraea sp. ATCC 39727, the producer of A40926 (the precursor for the semisynthetic dalbavancin), does not harbor the canonical vanHAX genes. Consequently, we investigated the role of the β-lactam-sensitive D,D-peptidase/D,D-carboxypeptidase encoded by vanYn, the only van-like gene found in the A40926 biosynthetic gene cluster, in conferring immunity to the antibiotic in Nonomuraea sp. ATCC 39727. Taking advantage of the tools developed recently to genetically manipulate this uncommon actinomycete, we varied vanYn gene dosage and expressed vanHatAatXat from the teicoplanin producer Actinoplanes teichomyceticus in Nonomuraea sp. ATCC 39727. Knocking out vanYn, complementing a vanYn mutant, or duplicating vanYn had no effect on growth but influenced antibiotic resistance and, in the cases of complementation and duplication, antibiotic production. Nonomuraea sp. ATCC 39727 was found to be resistant to penicillins, but its glycopeptide resistance was diminished in the presence of penicillin G, which inhibits VanYn activity. The heterologous expression of vanHatAatXat increased A40926 resistance in Nonomuraea sp. ATCC 39727 but did not increase antibiotic production, indicating that the level of antibiotic production is not directly determined by the level of resistance. The vanYn-based self-resistance in Nonomuraea sp. ATCC 39727 resembles the glycopeptide resistance mechanism described recently in mutants of Enterococcus faecium selected in vitro for high-level resistance to glycopeptides and penicillins.
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vanO, a new glycopeptide resistance operon in environmental Rhodococcus equi isolates. Antimicrob Agents Chemother 2013; 58:1768-70. [PMID: 24342631 DOI: 10.1128/aac.01880-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We describe here the sequence and gene organization of a new glycopeptide resistance operon (vanO) in Rhodococcus equi from soil. The vanO operon has low homology to enterococcal van operons and harbors a vanHOX cluster transcribed in the direction opposite that of the vanS-vanR regulatory system and composed of three open reading frames with unknown function. This finding has clinical interest, since glycopeptides are used to treat R. equi infections and resistance has been reported in clinical isolates.
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Yim G, Thaker MN, Koteva K, Wright G. Glycopeptide antibiotic biosynthesis. J Antibiot (Tokyo) 2013; 67:31-41. [DOI: 10.1038/ja.2013.117] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/10/2013] [Accepted: 10/15/2013] [Indexed: 11/09/2022]
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Abstract
Gene swapping is a simple but effective genetic tool for characterizing the functioning of a gene, where the gene in question is known to fulfil a distinctive biological role in the cell. VanS is a sensor kinase which, in conjunction with its cognate response regulator VanR, triggers resistance to vancomycin. One of the most important questions yet to be answered in the study of vancomycin resistance is the nature of the specific ligand recognized by the VanS sensor. A "VanRS-swap" experiment between two glycopeptide-resistant Streptomyces species known to exhibit differing responses to inducer molecules can investigate whether inducer specificity is determined solely by differences between the amino acid sequences of the VanRS two-component systems present, or by inherent differences in cell wall structure and biosynthesis between the strains. Results from such experiments demonstrate that inducer specificity is determined by the origin of the VanRS proteins and provides useful circumstantial evidence that the VanS effector ligand is the drug itself, and not an intermediate in cell wall biosynthesis that may accumulate as a result of drug action.
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Affiliation(s)
- Hee-Jeon Hong
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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Novel mechanism of glycopeptide resistance in the A40926 producer Nonomuraea sp. ATCC 39727. Antimicrob Agents Chemother 2010; 54:2465-72. [PMID: 20308385 DOI: 10.1128/aac.00106-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In glycopeptide-resistant enterococci and staphylococci, high-level resistance is achieved by replacing the C-terminal d-alanyl-d-alanine of lipid II with d-alanyl-d-lactate, thus reducing glycopeptide affinity for cell wall targets. Reorganization of the cell wall in these organisms is directed by the vanHAX gene cluster. Similar self-resistance mechanisms have been reported for glycopeptide-producing actinomycetes. We investigated glycopeptide resistance in Nonomuraea sp. ATCC 39727, the producer of the glycopeptide A40926, which is the precursor of the semisynthetic antibiotic dalbavancin, which is currently in phase III clinical trials. The MIC of Nonomuraea sp. ATCC 39727 toward A40926 during vegetative growth was 4 microg/ml, but this increased to ca. 20 microg/ml during A40926 production. vanHAX gene clusters were not detected in Nonomuraea sp. ATCC 39727 by Southern hybridization or by PCR with degenerate primers. However, the dbv gene cluster for A40926 production contains a gene, vanY (ORF7), potentially encoding an enzyme capable of removing the terminal d-Ala residue of pentapeptide peptidoglycan precursors. Analysis of UDP-linked peptidoglycan precursors in Nonomuraea sp. ATCC 39727 revealed the predominant presence of the tetrapeptide UDP-MurNAc-l-Ala-d-Glu-meso-Dap-d-Ala and only traces of the pentapeptide UDP-MurNAc-l-Ala-d-Glu-meso-Dap-d-Ala-d-Ala. This suggested a novel mechanism of glycopeptide resistance in Nonomuraea sp. ATCC 39727 that was based on the d,d-carboxypeptidase activity of vanY. Consistent with this, a vanY-null mutant of Nonomuraea sp. ATCC 39727 demonstrated a reduced level of glycopeptide resistance, without affecting A40926 productivity. Heterologous expression of vanY in a sensitive Streptomyces species, Streptomyces venezuelae, resulted in higher levels of glycopeptide resistance.
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Biosynthesis, biotechnological production, and application of teicoplanin: current state and perspectives. Appl Microbiol Biotechnol 2009; 84:417-28. [DOI: 10.1007/s00253-009-2107-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 06/19/2009] [Accepted: 06/21/2009] [Indexed: 11/26/2022]
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Vancomycin resistance VanS/VanR two-component systems. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 631:200-13. [PMID: 18792691 DOI: 10.1007/978-0-387-78885-2_14] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Vancomycin is a member of the glycopeptide class of antibiotics. Vancomycin resistance (van) gene clusters are found in human pathogens such as Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus, glycopeptide-producing actinomycetes such as Amycolotopsis orientalis, Actinoplanes teichomyceticus and Streptomyces toyocaensis and the nonglycopeptide producing actinomycete Streptomyces coelicolor. Expression of the van genes is activated by the VanS/VanR two-component system in response to extracellular glycopeptide antibiotic. Two major types of inducible vancomycin resistance are found in pathogenic bacteria; VanA strains are resistant to vancomycin itself and also to the lipidated glycopeptide teicoplanin, while VanB strains are resistant to vancomycin but sensitive to teicoplanin. Here we discuss the enzymes the van genes encode, the range of different VanS/VanR two-component systems, the biochemistry of VanS/VanR, the nature of the effector ligand(s) recognised by VanS and the evolution of the van cluster.
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Werner G, Strommenger B, Witte W. Acquired vancomycin resistance in clinically relevant pathogens. Future Microbiol 2008; 3:547-62. [DOI: 10.2217/17460913.3.5.547] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Acquired resistance to vancomycin is an increasing problem in pathogenic bacteria. It is best studied and most prevalent among Enterococcus and still remains rare in other pathogenic bacteria. Different genotypes of vancomycin resistance, vanA–G, have been described. The different van gene clusters consist of up to nine genes encoding proteins of different functions; their interplay leads to an alternative cell wall precursor less susceptible to glycopeptide binding. Variants of vanA and vanB types are found worldwide, with vanA predominating; their reservoir is Enterococcus faecium. Within this species a subpopulation of hospital-adapted types exists that acquired van gene clusters and which is responsible for outbreaks of vancomycin-resistant enterococci all over the world. Acquisition of vanA by methicillin-resistant Staphylococcus aureus (MRSA) is worrisome and seven cases have been described. Nonsusceptibility to glycopeptides also occurs independently from van genes and is a growing therapeutic challenge, especially in MRSA.
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Affiliation(s)
- Guido Werner
- FG 13 Nosocomial Infections, Robert Koch Institute, Wernigerode Branch, Burgstr. 37, Wernigerode, 38855, Germany
| | - Birgit Strommenger
- Robert Koch Institute, Wernigerode Branch, Burgstr. 37, Wernigerode, 38855, Germany
| | - Wolfgang Witte
- Robert Koch Institute, Wernigerode Branch, Burgstr. 37, Wernigerode, 38855, Germany
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Mainardi JL, Villet R, Bugg TD, Mayer C, Arthur M. Evolution of peptidoglycan biosynthesis under the selective pressure of antibiotics in Gram-positive bacteria. FEMS Microbiol Rev 2008; 32:386-408. [PMID: 18266857 DOI: 10.1111/j.1574-6976.2007.00097.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Acquisition of resistance to the two classes of antibiotics therapeutically used against Gram-positive bacteria, the glycopeptides and the beta-lactams, has revealed an unexpected flexibility in the peptidoglycan assembly pathway. Glycopeptides select for diversification of the fifth position of stem pentapeptides because replacement of D-Ala by D-lactate or D-Ser at this position prevents binding of the drugs to peptidoglycan precursors. The substitution is generally well tolerated by the classical D,D-transpeptidases belonging to the penicillin-binding protein family, except by low-affinity enzymes. Total elimination of the fifth residue by a D,D-carboxypeptidase requires a novel cross-linking enzyme able to process the resulting tetrapeptide stems. This enzyme, an L,D-transpeptidase, confers cross-resistance to beta-lactams and glycopeptides. Diversification of the side chain of the precursors, presumably in response to the selective pressure of peptidoglycan endopeptidases, is controlled by aminoacyl transferases of the Fem family that redirect specific aminoacyl-tRNAs from translation to peptidoglycan synthesis. Diversification of the side chains has been accompanied by a parallel divergent evolution of the substrate specificity of the L,D-transpeptidases, in contrast to the D,D-transpeptidases, which display an unexpected broad specificity. This review focuses on the role of antibiotics in selecting or counter-selecting diversification of the structure of peptidoglycan precursors and their mode of polymerization.
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Affiliation(s)
- Jean-Luc Mainardi
- INSERM, U872, LRMA, Centre de Recherche des Cordeliers, Paris, France
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Beltrametti F, Consolandi A, Carrano L, Bagatin F, Rossi R, Leoni L, Zennaro E, Selva E, Marinelli F. Resistance to glycopeptide antibiotics in the teicoplanin producer is mediated by van gene homologue expression directing the synthesis of a modified cell wall peptidoglycan. Antimicrob Agents Chemother 2007; 51:1135-41. [PMID: 17220405 PMCID: PMC1855507 DOI: 10.1128/aac.01071-06] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycopeptide resistance has been studied in detail in enterococci and staphylococci. In these microorganisms, high-level resistance is achieved by replacing the C-terminal D-alanyl-D-alanine of the nascent peptidoglycan with D-alanyl-D-lactate or D-alanyl-D-serine, thus reducing the affinities of glycopeptides for cell wall targets. Reorganization of the cell wall is directed by the expression of the van gene clusters. The identification of van gene homologs in the genomes of several glycopeptide-producing actinomycetes suggests the involvement of a similar self-resistance mechanism to avoid suicide. This report describes a comprehensive study of self-resistance in Actinoplanes teichomyceticus ATCC 31121, the producer of the clinically relevant glycopeptide teicoplanin. A. teichomyceticus ATCC 31121 showed a MIC of teicoplanin of 25 microg/ml and a MIC of vancomycin of 90 microg/ml during vegetative growth. The vanH, vanA, and vanX genes of A. teichomyceticus were found to be organized in an operon whose transcription was constitutive. Analysis of the UDP-linked peptidoglycan precursors revealed the presence of UDP-glycomuramyl pentadepsipeptide terminating in D-alanyl-D-lactate. No trace of precursors ending in d-alanyl-d-alanine was detected. Thus, the van gene complex was transcribed and expressed in the genetic background of A. teichomyceticus and conferred resistance to vancomycin and teicoplanin through the modification of cell wall biosynthesis. During teicoplanin production (maximum productivity, 70 to 80 microg/ml), the MIC of teicoplanin remained in the range of 25 to 35 microg/ml. Teicoplanin-producing cells were found to be tolerant to high concentrations of exogenously added glycopeptides, which were not bactericidal even at 5,000 microg/ml.
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Sosio M, Donadio S. Understanding and manipulating glycopeptide pathways: the example of the dalbavancin precursor A40926. J Ind Microbiol Biotechnol 2006; 33:569-76. [PMID: 16761167 DOI: 10.1007/s10295-006-0124-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 03/24/2006] [Indexed: 10/24/2022]
Abstract
Glycopeptide antibiotics represent an important class of microbial compounds produced by several genera of actinomycetes. The emergence of resistance to glycopeptides among enterococci and staphylococci has prompted the search for second-generation drugs of this class and semi-synthetic derivatives are currently under clinical trials. Dalbavancin is obtained by chemical modification of the natural glycopeptide A40926, produced by a Nonomuraea sp. Recently, there has been considerable progress in the elucidation of biosynthesis of glycopeptide antibiotics; several gene clusters have been characterized, thus providing an understanding of the biosynthesis of these chemically complex molecules. Furthermore, such investigations have yielded the first glycopeptide derivatives produced by genetic or enzymatic intervention. We have isolated and characterized the dbv clusters, involved in the formation of the glycopeptides A40926. The development of a gene-transfer system for Nonomuraea sp. has allowed the manipulation of the A40926 pathway. New derivatives were obtained by inactivating selected dbv genes. In addition, our data suggest differences in the biosynthetic routes for heptapeptide formation between the vancomycin and the teicoplanin families of glycopeptides.
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Affiliation(s)
- Margherita Sosio
- Vicuron Pharmaceuticals, via R. Lepetit 34, 21040 Gerenzano (VA), Italy.
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Hong HJ, Hutchings MI, Hill LM, Buttner MJ. The role of the novel Fem protein VanK in vancomycin resistance in Streptomyces coelicolor. J Biol Chem 2005; 280:13055-61. [PMID: 15632111 DOI: 10.1074/jbc.m413801200] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The non-pathogenic, non-glycopeptide-producing actinomycete Streptomyces coelicolor carries a cluster of seven genes (vanSRJKHAX) that confers inducible, high level resistance to vancomycin. The vanK gene has no counterpart in previously characterized vancomycin resistance clusters, yet vanK is required for vancomycin resistance in S. coelicolor. VanK belongs to the Fem family of enzymes, which add the branch amino acid(s) to the stem pentapeptide of peptidoglycan precursors. Upon exposure to vancomycin, the VanRS two-component system switches on expression of all seven van genes, and the VanHAX enzymes reprogram the cell wall such that precursors terminate D-Ala-D-lactate (Lac) rather than D-Ala-D-Ala, thus conferring resistance to vancomycin, which only binds D-Ala-D-Ala-containing precursors. Here we provide biochemical and genetic evidence that VanK is required for vancomycin resistance because the constitutively expressed FemX enzyme, encoded elsewhere on the chromosome, cannot recognize D-Lac-containing precursors as a substrate, whereas VanK can. Consistent with this view, D-Lac-containing precursors carrying the Gly branch are present in the wild type transiently exposed to vancomycin but are undetectable in a vanK mutant treated in the same way. Further, femX null mutants are viable in the presence of vancomycin but die in its absence. Because only VanK can recognize D-Lac-containing precursors, vancomycin-induced expression of VanHAX in a vanK mutant is lethal, and so vanK is required for vancomycin resistance.
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Affiliation(s)
- Hee-Jeon Hong
- Department of Molecular Microbiology, John Innes Centre, Colney, Norwich NR4 7UH, United Kingdom.
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