# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 3 | 0 | 0.8766 | Noncanonical coproporphyrin-dependent bacterial heme biosynthesis pathway that does not use protoporphyrin. It has been generally accepted that biosynthesis of protoheme (heme) uses a common set of core metabolic intermediates that includes protoporphyrin. Herein, we show that the Actinobacteria and Firmicutes (high-GC and low-GC Gram-positive bacteria) are unable to synthesize protoporphyrin. Instead, they oxidize coproporphyrinogen to coproporphyrin, insert ferrous iron to make Fe-coproporphyrin (coproheme), and then decarboxylate coproheme to generate protoheme. This pathway is specified by three genes named hemY, hemH, and hemQ. The analysis of 982 representative prokaryotic genomes is consistent with this pathway being the most ancient heme synthesis pathway in the Eubacteria. Our results identifying a previously unknown branch of tetrapyrrole synthesis support a significant shift from current models for the evolution of bacterial heme and chlorophyll synthesis. Because some organisms that possess this coproporphyrin-dependent branch are major causes of human disease, HemQ is a novel pharmacological target of significant therapeutic relevance, particularly given high rates of antimicrobial resistance among these pathogens. | 2015 | 25646457 |
| 4361 | 1 | 0.8750 | A rifamycin inactivating phosphotransferase family shared by environmental and pathogenic bacteria. Many environmental bacteria are multidrug-resistant and represent a reservoir of ancient antibiotic resistance determinants, which have been linked to genes found in pathogens. Exploring the environmental antibiotic resistome, therefore, reveals the diversity and evolution of antibiotic resistance and also provides insight into the vulnerability of clinically used antibiotics. In this study, we describe the identification of a highly conserved regulatory motif, the rifampin (RIF) -associated element (RAE), which is found upstream of genes encoding RIF-inactivating enzymes from a diverse collection of actinomycetes. Using gene expression assays, we confirmed that the RAE is involved in RIF-responsive regulation. By using the RAE as a probe for new RIF-associated genes in several actinomycete genomes, we identified a heretofore unknown RIF resistance gene, RIF phosphotransferase (rph). The RPH enzyme is a RIF-inactivating phosphotransferase and represents a new protein family in antibiotic resistance. RPH orthologs are widespread and found in RIF-sensitive bacteria, including Bacillus cereus and the pathogen Listeria monocytogenes. Heterologous expression and in vitro enzyme assays with purified RPHs from diverse bacterial genera show that these enzymes are capable of conferring high-level resistance to a variety of clinically used rifamycin antibiotics. This work identifies a new antibiotic resistance protein family and reinforces the fact that the study of resistance in environmental organisms can serve to identify resistance elements with relevance to pathogens. | 2014 | 24778229 |
| 122 | 2 | 0.8744 | Functional characterization of ORCTL2--an organic cation transporter expressed in the renal proximal tubules. Chromosome 11p15.5 harbors a gene or genes involved in Beckwith-Wiedemann syndrome that confer(s) susceptibility to Wilms' tumor, rhabdomyosarcoma, and hepatoblastoma. We have previously identified a transcript at 11p15.5 which encodes a putative membrane transport protein, designated organic cation transporter-like 2 (ORCTL2), that shares homology with tetracycline resistance proteins and bacterial multidrug resistance proteins. In this report, we have investigated the transport properties of ORCTL2 and show that this protein can confer resistance to chloroquine and quinidine when overexpressed in bacteria. Immunohistochemistry analyses performed with anti-ORCTL2 polyclonal antibodies on human renal sections indicate that ORCTL2 is localized on the apical membrane surface of the proximal tubules. These results suggest that ORCTL2 may play a role in the transport of chloroquine and quinidine related compounds in the kidney. | 1998 | 9744804 |
| 607 | 3 | 0.8736 | A novel copper-sensing two-component system for inducing Dsb gene expression in bacteria. In nature, bacteria must sense copper and tightly regulate gene expression to evade copper toxicity. Here, we identify a new copper-responsive two-component system named DsbRS in the important human pathogen Pseudomonas aeruginosa; in this system, DsbS is a sensor histidine kinase, and DsbR, its cognate response regulator, directly induces the transcription of genes involved in protein disulfide bond formation (Dsb) (i.e., the dsbDEG operon and dsbB). In the absence of copper, DsbS acts as a phosphatase toward DsbR, thus blocking the transcription of Dsb genes. In the presence of copper, the metal ion directly binds to the sensor domain of DsbS, and the Cys82 residue plays a critical role in this process. The copper-binding behavior appears to inhibit the phosphatase activity of DsbS, leading to the activation of DsbR. The copper resistance of the dsbRS knock-out mutant is restored by the ectopic expression of the dsbDEG operon, which is a DsbRS major target. Strikingly, cognates of the dsbRS-dsbDEG pair are widely distributed across eubacteria. In addition, a DsbR-binding site, which contains the consensus sequence 5'-TTA-N(8)-TTAA-3', is detected in the promoter region of dsbDEG homologs in these species. These findings suggest that the regulation of Dsb genes by DsbRS represents a novel mechanism by which bacterial cells cope with copper stress. | 2022 | 36546013 |
| 513 | 4 | 0.8722 | New mechanisms of bacterial arsenic resistance. Arsenic is the most pervasive environmental substance and is classified by the International Agency for Research on Cancer as a Group 1 human carcinogen. Nearly every organism has resistance pathways for inorganic arsenic, and in bacteria, their genes are found in arsenic resistance (ars) operons. Recently, a parallel pathway for organic arsenicals has been identified. The ars genes responsible for the organoarsenical detoxification includes arsM, which encodes an As(III) S-adenosylmethionine methyltransferase, arsI, which encodes a C-As bond lyase, and arsH, which encodes a methylarsenite oxidase. The identification and properties of arsM, arsI and arsH are described in this review. | 2016 | 27105594 |
| 514 | 5 | 0.8719 | The organoarsenical biocycle and the primordial antibiotic methylarsenite. Arsenic is the most pervasive environmental toxic substance. As a consequence of its ubiquity, nearly every organism has genes for resistance to inorganic arsenic. In bacteria these genes are found largely in bacterial arsenic resistance (ars) operons. Recently a parallel pathway for synthesis and degradation of methylated arsenicals has been identified. The arsM gene product encodes the ArsM (AS3MT in animals) As(iii) S-adenosylmethionine methyltransferase that methylates inorganic trivalent arsenite in three sequential steps to methylarsenite MAs(iii), dimethylarsenite (DMAs(iii) and trimethylarsenite (TMAs(iii)). MAs(iii) is considerably more toxic than As(iii), and we have proposed that MAs(iii) was a primordial antibiotic. Under aerobic conditions these products are oxidized to nontoxic pentavalent arsenicals, so that methylation became a detoxifying pathway after the atmosphere became oxidizing. Other microbes have acquired the ability to regenerate MAs(v) by reduction, transforming it again into toxic MAs(iii). Under this environmental pressure, MAs(iii) resistances evolved, including the arsI, arsH and arsP genes. ArsI is a C-As bond lyase that demethylates MAs(iii) back to less toxic As(iii). ArsH re-oxidizes MAs(iii) to MAs(v). ArsP actively extrudes MAs(iii) from cells. These proteins confer resistance to this primitive antibiotic. This oscillation between MAs(iii) synthesis and detoxification is an essential component of the arsenic biogeocycle. | 2016 | 27730229 |
| 549 | 6 | 0.8709 | Extracytoplasmic function sigma factor σ(D) confers resistance to environmental stress by enhancing mycolate synthesis and modifying peptidoglycan structures in Corynebacterium glutamicum. Mycolates are α-branched, β-hydroxylated, long-chain fatty acid specifically synthesized in bacteria in the suborder Corynebacterineae of the phylum Actinobacteria. They form an outer membrane, which functions as a permeability barrier and confers pathogenic mycobacteria to resistance to antibiotics. Although the mycolate biosynthetic pathway has been intensively studied, knowledge of transcriptional regulation of genes involved in this pathway is limited. Here, we report that the extracytoplasmic function sigma factor σ(D) is a key regulator of the mycolate synthetic genes in Corynebacterium glutamicum in the suborder. Chromatin immunoprecipitation with microarray analysis detected σ(D) -binding regions in the genome, establishing a consensus promoter sequence for σ(D) recognition. The σ(D) regulon comprised acyl-CoA carboxylase subunits, acyl-AMP ligase, polyketide synthase and mycolyltransferases; they were involved in mycolate synthesis. Indeed, deletion or overexpression of sigD encoding σ(D) modified the extractable mycolate amount. Immediately downstream of sigD, rsdA encoded anti-σ(D) and was under the control of a σ(D) -dependent promoter. Another σ(D) regulon member, l,d-transpeptidase, conferred lysozyme resistance. Thus, σ(D) modifies peptidoglycan cross-linking and enhances mycolate synthesis to provide resistance to environmental stress. | 2018 | 29148103 |
| 543 | 7 | 0.8708 | OxyR2 Modulates OxyR1 Activity and Vibrio cholerae Oxidative Stress Response. Bacteria have developed capacities to deal with different stresses and adapt to different environmental niches. The human pathogen Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, utilizes the transcriptional regulator OxyR to activate genes related to oxidative stress resistance, including peroxiredoxin PrxA, in response to hydrogen peroxide. In this study, we identified another OxyR homolog in V. cholerae, which we named OxyR2, and we renamed the previous OxyR OxyR1. We found that OxyR2 is required to activate its divergently transcribed gene ahpC, encoding an alkylhydroperoxide reductase, independently of H(2)O(2) A conserved cysteine residue in OxyR2 is critical for this function. Mutation of either oxyR2 or ahpC rendered V. cholerae more resistant to H(2)O(2) RNA sequencing analyses indicated that OxyR1-activated oxidative stress-resistant genes were highly expressed in oxyR2 mutants even in the absence of H(2)O(2) Further genetic analyses suggest that OxyR2-activated AhpC modulates OxyR1 activity by maintaining low intracellular concentrations of H(2)O(2) Furthermore, we showed that ΔoxyR2 and ΔahpC mutants were less fit when anaerobically grown bacteria were exposed to low levels of H(2)O(2) or incubated in seawater. These results suggest that OxyR2 and AhpC play important roles in the V. cholerae oxidative stress response. | 2017 | 28138024 |
| 6078 | 8 | 0.8705 | Genomic Insights into Cyanide Biodegradation in the Pseudomonas Genus. Molecular studies about cyanide biodegradation have been mainly focused on the hydrolytic pathways catalyzed by the cyanide dihydratase CynD or the nitrilase NitC. In some Pseudomonas strains, the assimilation of cyanide has been linked to NitC, such as the cyanotrophic model strain Pseudomonas pseudoalcaligenes CECT 5344, which has been recently reclassified as Pseudomonas oleovorans CECT 5344. In this work, a phylogenomic approach established a more precise taxonomic position of the strain CECT 5344 within the species P. oleovorans. Furthermore, a pan-genomic analysis of P. oleovorans and other species with cyanotrophic strains, such as P. fluorescens and P. monteilii, allowed for the comparison and identification of the cioAB and mqoAB genes involved in cyanide resistance, and the nitC and cynS genes required for the assimilation of cyanide or cyanate, respectively. While cyanide resistance genes presented a high frequency among the analyzed genomes, genes responsible for cyanide or cyanate assimilation were identified in a considerably lower proportion. According to the results obtained in this work, an in silico approach based on a comparative genomic approach can be considered as an agile strategy for the bioprospection of putative cyanotrophic bacteria and for the identification of new genes putatively involved in cyanide biodegradation. | 2024 | 38674043 |
| 803 | 9 | 0.8704 | Nucleotide sequences and genetic analysis of hydrogen oxidation (hox) genes in Azotobacter vinelandii. Azotobacter vinelandii contains a heterodimeric, membrane-bound [NiFe]hydrogenase capable of catalyzing the reversible oxidation of H2. The beta and alpha subunits of the enzyme are encoded by the structural genes hoxK and hoxG, respectively, which appear to form part of an operon that contains at least one further potential gene (open reading frame 3 [ORF3]). In this study, determination of the nucleotide sequence of a region of 2,344 bp downstream of ORF3 revealed four additional closely spaced or overlapping ORFs. These ORFs, ORF4 through ORF7, potentially encode polypeptides with predicted masses of 22.8, 11.4, 16.3, and 31 kDa, respectively. Mutagenesis of the chromosome of A. vinelandii in the area sequenced was carried out by introduction of antibiotic resistance gene cassettes. Disruption of hoxK and hoxG by a kanamycin resistance gene abolished whole-cell hydrogenase activity coupled to O2 and led to loss of the hydrogenase alpha subunit. Insertional mutagenesis of ORF3 through ORF7 with a promoterless lacZ-Kmr cassette established that the region is transcriptionally active and involved in H2 oxidation. We propose to call ORF3 through ORF7 hoxZ, hoxM, hoxL, hoxO, and hoxQ, respectively. The predicted hox gene products resemble those encoded by genes from hydrogenase-related operons in other bacteria, including Escherichia coli and Alcaligenes eutrophus. | 1992 | 1624446 |
| 132 | 10 | 0.8699 | Chromium resistance strategies and toxicity: what makes Ochrobactrum tritici 5bvl1 a strain highly resistant. Large-scale industrial use of chromium (Cr) resulted in widespread environmental contamination with hexavalent chromium (Cr(VI)). The ability of microorganisms to survive in these environments and detoxify chromate requires the presence of specific resistance systems. Several Cr(VI) resistant species, belonging to a variety of genera, have been isolated in recent years. Ochrobactrum tritici strain 5bvl1 is a model for a highly Cr(VI)-resistant and reducing microorganism, with different strategies to cope with chromium. The strain contains the transposon-located (TnOtChr) chromate resistance genes chrB, chrA, chrC, chrF. The chrB and chrA genes were found to be essential for the establishment of high resistance but not chrC or chrF genes. Other mechanisms involved in chromium resistance in this strain were related to strategies such as specific or unspecific Cr(VI) reduction, free-radical detoxifying activities, and repairing DNA damage. Expression of the chrB, chrC or chrF genes was related to increased resistance to superoxide-generating agents. Genetic analyses also showed that, the ruvB gene is related to chromium resistance in O. tritici 5bvl1. The RuvABC complex probably does not form when ruvB gene is interrupted, and the repair of DNA damage induced by chromium is prevented. Aerobic or anaerobic chromate reductase activity and other unspecific mechanisms for chromium reduction have been identified in different bacteria. In the strain O. tritici 5bvl1, several unspecific mechanisms were found. Dichromate and chromate have different effects on the physiology of the chromium resistant strains and dichromate seems to be more toxic. Toxicity of Cr(VI) was evaluated by following growth, reduction, respiration, glucose uptake assays and by comparing cell morphology. | 2011 | 21472416 |
| 605 | 11 | 0.8698 | Conservation and diversity of the IrrE/DdrO-controlled radiation response in radiation-resistant Deinococcus bacteria. The extreme radiation resistance of Deinococcus bacteria requires the radiation-stimulated cleavage of protein DdrO by a specific metalloprotease called IrrE. DdrO is the repressor of a predicted radiation/desiccation response (RDR) regulon, composed of radiation-induced genes having a conserved DNA motif (RDRM) in their promoter regions. Here, we showed that addition of zinc ions to purified apo-IrrE, and short exposure of Deinococcus cells to zinc ions, resulted in cleavage of DdrO in vitro and in vivo, respectively. Binding of IrrE to RDRM-containing DNA or interaction of IrrE with DNA-bound DdrO was not observed. The data are in line with IrrE being a zinc peptidase, and indicate that increased zinc availability, caused by oxidative stress, triggers the in vivo cleavage of DdrO unbound to DNA. Transcriptomics and proteomics of Deinococcus deserti confirmed the IrrE-dependent regulation of predicted RDR regulon genes and also revealed additional members of this regulon. Comparative analysis showed that the RDR regulon is largely well conserved in Deinococcus species, but also showed diversity in the regulon composition. Notably, several RDR genes with an important role in radiation resistance in Deinococcus radiodurans, for example pprA, are not conserved in some other radiation-resistant Deinococcus species. | 2017 | 28397370 |
| 517 | 12 | 0.8698 | Adaptation to metal(loid)s in strain Mucilaginibacter rubeus P2 involves novel arsenic resistance genes and mechanisms. Arsenic is a ubiquitous environmental toxi substance that affects human health. Compared to inorganic arsenicals, reduced organoarsenicals are more toxic, and some of them are recognized as antibiotics, such as methylarsenite [MAs(III)] and arsinothricin (2-amino-4-(hydroxymethylarsinoyl)butanoate, or AST). To date, organoarsenicals such as MAs(V) and roxarsone [Rox(V)] are still used in agriculture and animal husbandry. How bacteria deal with both inorganic and organoarsenic species is unclear. Recently, we identified an environmental isolate Mucilaginibacter rubeus P2 that has adapted to high arsenic and antinomy levels by triplicating an arsR-mrarsU(Bact)-arsN-arsC-(arsRhp)-hp-acr3-mrme1(Bact)-mrme2(Bact)gene cluster. Heterologous expression of mrarsM(Bact), mrarsU(Bact), mrme1(Bact) and mrme2(Bact), encoding putative arsenic resistance determinants, in the arsenic hypersensitive strain Escherichia coli AW3110 conferred resistance to As(III), As(V), MAs(III) or Rox(III). Our data suggest that metalloid exposure promotes plasticity in arsenic resistance systems, enhancing host organism adaptation to metalloid stress. | 2024 | 37865075 |
| 5188 | 13 | 0.8696 | Zoonotic bacterial and parasitic intestinal pathogens in foxes, raccoons and other predators from eastern Germany. In this study, we investigated faecal specimens from legally hunted and road-killed red foxes, raccoons, raccoon dogs, badgers and martens in Germany for parasites and selected zoonotic bacteria. We found that Baylisascaris procyonis, a zoonotic parasite of raccoons, had spread to northeastern Germany, an area previously presumed to be free of this parasite. We detected various pathogenic bacterial species from the genera Listeria, Clostridium (including baratii), Yersinia and Salmonella, which were analysed using whole-genome sequencing. One isolate of Yersinia enterocolitica contained a virulence plasmid. The Salmonella Cholerasuis isolate encoded an aminoglycoside resistance gene and a parC point mutation, conferring resistance to ciprofloxacin. We also found tetracycline resistance genes in Paeniclostridium sordellii and Clostridium baratii. Phylogenetic analyses revealed that the isolates were polyclonal, indicating the absence of specific wildlife-adapted clones. Predators, which scavenge from various sources including human settlements, acquire and spread zoonotic pathogens. Therefore, their role should not be overlooked in the One Health context. | 2024 | 38747071 |
| 8643 | 14 | 0.8692 | Diversity of Phototrophic Genes Suggests Multiple Bacteria May Be Able to Exploit Sunlight in Exposed Soils from the Sør Rondane Mountains, East Antarctica. Microbial life in exposed terrestrial surface layers in continental Antarctica is faced with extreme environmental conditions, including scarcity of organic matter. Bacteria in these exposed settings can therefore be expected to use alternative energy sources such as solar energy, abundant during the austral summer. Using Illumina MiSeq sequencing, we assessed the diversity and abundance of four conserved protein encoding genes involved in different key steps of light-harvesting pathways dependent on (bacterio)chlorophyll (pufM, bchL/chlL, and bchX genes) and rhodopsins (actinorhodopsin genes), in exposed soils from the Sør Rondane Mountains, East Antarctica. Analysis of pufM genes, encoding a subunit of the type 2 photochemical reaction center found in anoxygenic phototrophic bacteria, revealed a broad diversity, dominated by Roseobacter- and Loktanella-like sequences. The bchL and chlL, involved in (bacterio)chlorophyll synthesis, on the other hand, showed a high relative abundance of either cyanobacterial or green algal trebouxiophyceael chlL reads, depending on the sample, while most bchX sequences belonged mostly to previously unidentified phylotypes. Rhodopsin-containing phototrophic bacteria could not be detected in the samples. Our results, while suggesting that Cyanobacteria and green algae are the main phototrophic groups, show that light-harvesting bacteria are nevertheless very diverse in microbial communities in Antarctic soils. | 2016 | 28066352 |
| 6191 | 15 | 0.8689 | Involvement of the leucine response transcription factor LeuO in regulation of the genes for sulfa drug efflux. LeuO, a LysR family transcription factor, exists in a wide variety of bacteria of the family Enterobacteriaceae and is involved in the regulation of as yet unidentified genes affecting the stress response and pathogenesis expression. Using genomic screening by systematic evolution of ligands by exponential enrichment (SELEX) in vitro, a total of 106 DNA sequences were isolated from 12 different regions of the Escherichia coli genome. All of the SELEX fragments formed complexes in vitro with purified LeuO. After Northern blot analysis of the putative target genes located downstream of the respective LeuO-binding sequence, a total of nine genes were found to be activated by LeuO, while three genes were repressed by LeuO. The LeuO target gene collection included several multidrug resistance genes. A phenotype microarray assay was conducted to identify the gene(s) responsible for drug resistance and the drug species that are under the control of the LeuO target gene(s). The results described herein indicate that the yjcRQP operon, one of the LeuO targets, is involved in sensitivity control against sulfa drugs. We propose to rename the yjcRQP genes the sdsRQP genes (sulfa drug sensitivity determinant). | 2009 | 19429622 |
| 3741 | 16 | 0.8689 | The fib locus in Streptococcus pneumoniae is required for peptidoglycan crosslinking and PBP-mediated beta-lactam resistance. Penicillin resistance in pneumococci is mediated by modified penicillin-binding proteins (PBPs) that have decreased affinity to beta-lactams. In high-level penicillin-resistant transformants of the laboratory strain Streptococcus pneumoniae R6 containing various combinations of low-affinity PBPs, disruption of the fib locus results in a collapse of PBP-mediated resistance. In addition, crosslinked muropeptides are highly reduced. The fib operon consists of two genes, fibA and fibB, homologous to Staphylococcus aureus femA/B which are also required for expression of methicillin resistance in this organism. FibA and FibB belong to a family of proteins of Gram-positive bacteria involved in the formation of interpeptide bridges, thus representing interesting new targets for antimicrobial compounds for this group of pathogens. | 2000 | 10867238 |
| 802 | 17 | 0.8688 | YqhC regulates transcription of the adjacent Escherichia coli genes yqhD and dkgA that are involved in furfural tolerance. Previous results have demonstrated that the silencing of adjacent genes encoding NADPH-dependent furfural oxidoreductases (yqhD dkgA) is responsible for increased furfural tolerance in an E. coli strain EMFR9 [Miller et al., Appl Environ Microbiol 75:4315-4323, 2009]. This gene silencing is now reported to result from the spontaneous insertion of an IS10 into the coding region of yqhC, an upstream gene. YqhC shares homology with transcriptional regulators belonging to the AraC/XylS family and was shown to act as a positive regulator of the adjacent operon encoding YqhD and DkgA. Regulation was demonstrated by constructing a chromosomal deletion of yqhC, a firefly luciferase reporter plasmid for yqhC, and by a direct comparison of furfural resistance and NADPH-dependent furfural reductase activity. Closely related bacteria contain yqhC, yqhD, and dkgA orthologs in the same arrangement as in E. coli LY180. Orthologs of yqhC are also present in more distantly related Gram-negative bacteria. Disruption of yqhC offers a useful approach to increase furfural tolerance in bacteria. | 2011 | 20676725 |
| 558 | 18 | 0.8686 | Thiamine pyrophosphate riboswitches are targets for the antimicrobial compound pyrithiamine. Thiamine metabolism genes are regulated in numerous bacteria by a riboswitch class that binds the coenzyme thiamine pyrophosphate (TPP). We demonstrate that the antimicrobial action of the thiamine analog pyrithiamine (PT) is mediated by interaction with TPP riboswitches in bacteria and fungi. For example, pyrithiamine pyrophosphate (PTPP) binds the TPP riboswitch controlling the tenA operon in Bacillus subtilis. Expression of a TPP riboswitch-regulated reporter gene is reduced in transgenic B. subtilis or Escherichia coli when grown in the presence of thiamine or PT, while mutant riboswitches in these organisms are unresponsive to these ligands. Bacteria selected for PT resistance bear specific mutations that disrupt ligand binding to TPP riboswitches and derepress certain TPP metabolic genes. Our findings demonstrate that riboswitches can serve as antimicrobial drug targets and expand our understanding of thiamine metabolism in bacteria. | 2005 | 16356850 |
| 498 | 19 | 0.8686 | Noncanonical vancomycin resistance cluster from Desulfitobacterium hafniense Y51. The glycopeptide vancomycin is a drug of last resort for infection with gram-positive organisms, and three genes are vital to resistance: vanH, vanA, and vanX. These genes are found in a vanHAX cluster, which is conserved across pathogenic bacteria, glycopeptide antibiotic producers, and other environmental bacteria. The genome sequence of the anaerobic, gram-positive, dehalogenating bacterium Desulfitobacterium hafniense Y51 revealed a predicted vanA homolog; however, it exists in a vanAWK-murFX cluster, unlike those of other vancomycin-resistant organisms. Using purified recombinant VanA from D. hafniense Y51, we determined its substrate specificity and found it to have a 42-fold preference for D-lactate over D-alanine, confirming its activity as a D-Ala-D-Lac ligase and its annotation as VanA. Furthermore, we showed that D. hafniense Y51 is highly resistant to vancomycin, with a MIC for growth of 64 microg/ml. Finally, vanA(Dh) is expressed during growth in vancomycin, as demonstrated by reverse transcription-PCR. This finding represents a new glycopeptide antibiotic resistance gene cluster and expands the genetic diversity of resistance to this important class of antibiotic. | 2009 | 19414574 |