# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 467 | 0 | 0.9377 | Aerobic anoxygenic photosynthesis genes and operons in uncultured bacteria in the Delaware River. Photosynthesis genes and operons of aerobic anoxygenic photosynthetic (AAP) bacteria have been examined in a variety of marine habitats, but genomic information about freshwater AAP bacteria is lacking. The goal of this study was to examine photosynthesis genes of AAP bacteria in the Delaware River. In a fosmid library, we found two clones bearing photosynthesis gene clusters with unique gene content and organization. Both clones contained 37 open reading frames, with most of those genes encoding known AAP bacterial proteins. The genes in one fosmid were most closely related to those of AAP bacteria in the Rhodobacter genus. The genes of the other clone were related to those of freshwater beta-proteobacteria. Both clones contained the acsF gene, which is required for aerobic bacteriochlorophyll synthesis, suggesting that these bacteria are not anaerobes. The beta-proteobacterial fosmid has the puf operon B-A-L-M-C and is the first example of an uncultured bacterium with this operon structure. The alpha-3-proteobacterial fosmid has a rare gene order (Q-B-A-L-M-X), previously observed only in the Rhodobacter genus. Phylogenetic analyses of photosynthesis genes revealed a possible freshwater cluster of AAP beta-proteobacteria. The data from both Delaware River clones suggest there are groups of freshwater or estuarine AAP bacteria distinct from those found in marine environments. | 2005 | 16309388 |
| 8419 | 1 | 0.9373 | The uncultured luminous symbiont of Anomalops katoptron (Beryciformes: Anomalopidae) represents a new bacterial genus. Flashlight fishes (Beryciformes: Anomalopidae) harbor luminous symbiotic bacteria in subocular light organs and use the bacterial light for predator avoidance, feeding, and communication. Despite many attempts anomalopid symbionts have not been brought into laboratory culture, which has restricted progress in understanding their phylogenetic relationships with other luminous bacteria, identification of the genes of their luminescence system, as well as the nature of their symbiotic interactions with their fish hosts. To begin addressing these issues, we used culture-independent analysis of the bacteria symbiotic with the anomalopid fish, Anomalops katoptron, to characterize the phylogeny of the bacteria and to identify the genes of their luminescence system including those involved in the regulation of luminescence. Analysis of the 16S rRNA, atpA, gapA, gyrB, pyrH, recA, rpoA, and topA genes resolved the A. katoptron symbionts as a clade nested within and deeply divergent from other members of Vibrionaceae. The bacterial luminescence (lux) genes were identified as a contiguous set (luxCDABEG), as found for the lux operons of other luminous bacteria. Phylogenetic analysis based on the lux genes confirmed the housekeeping gene phylogenetic placement. Furthermore, genes flanking the lux operon in the A. katoptron symbionts differed from those flanking lux operons of other genera of luminous bacteria. We therefore propose the candidate name Candidatus Photodesmus (Greek: photo = light, desmus = servant) katoptron for the species of bacteria symbiotic with A. katoptron. Results of a preliminary genomic analysis for genes regulating luminescence in other bacteria identified only a Vibrio harveyi-type luxR gene. These results suggest that expression of the luminescence system might be continuous in P. katoptron. | 2011 | 21864694 |
| 129 | 2 | 0.9371 | Evidence for vital role of endo-β-N-acetylglucosaminidase in the resistance of Arthrobacter protophormiae RKJ100 towards elevated concentrations of o-nitrobenzoate. Arthrobacter protophormiae RKJ100 was previously characterized for its ability to tolerate extremely high concentrations of o-nitrobenzoate (ONB), a toxic xenobiotic environmental pollutant. The physiological responses of strain RKJ100 to ≥30 mM ONB indicated towards a resistance mechanism manifested via alteration of cell morphology and cell wall structure. In this study, we aim to characterize gene(s) involved in the resistance of strain RKJ100 towards extreme concentrations (i.e. 150 mM) of ONB. Transposon mutagenesis was carried out to generate a mutant library of strain RKJ100, which was then screened for ONB-sensitive mutants. A sensitive mutant was defined and selected as one that could not tolerate ≥30 mM ONB. Molecular and biochemical characterization of this mutant showed that the disruption of endo-β-N-acetylglucosaminidase (ENGase) gene caused the sensitivity. ENGase is an important enzyme for oligosaccharide processing and cell wall recycling in bacteria, fungi, plants and animals. Previous reports have already indicated several possible roles of this enzyme in cellular homeostasis. Results presented here provide the first evidence for its involvement in bacterial resistance towards extreme concentrations of a toxic xenobiotic compound and also suggest that strain RKJ100 employs ENGase as an important component in osmotic shock response for resisting extreme concentrations of ONB. | 2014 | 24562786 |
| 460 | 3 | 0.9368 | Horizontal transfer of the photosynthesis gene cluster and operon rearrangement in purple bacteria. A 37-kb photosynthesis gene cluster was sequenced in a photosynthetic bacterium belonging to the beta subclass of purple bacteria (Proteobacteria), Rubrivivax gelatinosus. The cluster contained 12 bacteriochlorophyll biosynthesis genes (bch), 7 carotenoid biosynthesis genes (crt), structural genes for photosynthetic apparatuses (puf and puh), and some other related genes. The gene arrangement was markedly different from those of other purple photosynthetic bacteria, while two superoperonal structures, crtEF-bchCXYZ-puf and bchFNBHLM-lhaA-puhA, were conserved. Molecular phylogenetic analyses of these photosynthesis genes showed that the photosynthesis gene cluster of Rvi. gelatinosus was originated from those of the species belonging to the alpha subclass of purple bacteria. It was concluded that a horizontal transfer of the photosynthesis gene cluster from an ancestral species belonging to the alpha subclass to that of the beta subclass of purple bacteria had occurred and was followed by rearrangements of the operons in this cluster. | 2001 | 11343129 |
| 194 | 4 | 0.9354 | Possible Role of CHAD Proteins in Copper Resistance. Conserved Histidine Alpha-helical Domain (CHAD) proteins attached to the surface of polyphosphate (PolyP) have been studied in some bacteria and one archaeon. However, the activity of CHAD proteins is unknown beyond their interaction with PolyP granules. By using bioinformatic analysis, we report that several species of the biomining acidophilic bacteria contain orthologs of CHAD proteins with high sequence identity. Furthermore, the gene coding for the CHAD protein is in the same genetic context of the enzyme polyphosphate kinase (PPK), which is in charge of PolyP synthesis. Particularly, the group of ppk and CHAD genes is highly conserved. Metallosphaera sedula and other acidophilic archaea used in biomining also contain CHAD proteins. These archaea show high levels of identity in genes coding for a cluster having the same organization. Amongst these genes are chad and ppx. In general, both biomining bacteria and archaea contain high PolyP levels and are highly resistant to heavy metals. Therefore, the presence of this conserved genetic organization suggests a high relevance for their metabolism. It has been formerly reported that a crystallized CHAD protein contains a copper-binding site. Based on this previous knowledge, in the present report, it was determined that all analyzed CHAD proteins are very conserved at their structural level. In addition, it was found that the lack of YgiF, an Escherichia coli CHAD-containing protein, decreases copper resistance in this bacterium. This phenotype was not only complemented by transforming E. coli with YgiF but also by expressing CHAD from Acidithiobacillus ferrooxidans in it. Interestingly, the strains in which the possible copper-binding sites were mutated were also more metal sensitive. Based on these results, we propose that CHAD proteins are involved in copper resistance in microorganisms. These findings are very interesting and may eventually improve biomining operations in the future. | 2024 | 38399813 |
| 614 | 5 | 0.9353 | Ehrlichia chaffeensis and Anaplasma phagocytophilum lack genes for lipid A biosynthesis and incorporate cholesterol for their survival. Ehrlichia chaffeensis and Anaplasma phagocytophilum are agents of human monocytic and granulocytic ehrlichioses, respectively. They are extremely sensitive to mechanical stress and are pleomorphic gram-negative bacteria. Membrane incorporation of cholesterol from the eukaryotic host is known to be essential for other fragile and pleomorphic bacteria and mycoplasmas that lack a cell wall. Thus, we tested whether cholesterol is required for E. chaffeensis and A. phagocytophilum. Using a freeze fracture technique and biochemical analysis, these bacteria were found to contain significant levels of membrane cholesterol. These bacteria lack genes for cholesterol biosynthesis or modification. However, host cell-free bacteria had the ability to take up directly exogenous cholesterol or NBD-cholesterol, a fluorescent cholesterol derivative. Treatment of the bacteria with cholesterol extraction reagent methyl-beta-cyclodextrin caused their ultrastructural changes. Furthermore, pretreatment of the bacteria with methyl-beta-cyclodextrin or NBD-cholesterol deprived these bacteria of the ability to infect leukocytes, thus killing these obligate intracellular bacteria. Analysis of E. chaffeensis and A. phagocytophilum genome sequences revealed that these bacteria lack all genes for the biosynthesis of lipid A and most genes for the biosynthesis of peptidoglycan, which confer structural strength to gram-negative bacteria. Taken together, these results suggest that human ehrlichiosis agents became cholesterol dependent due to the loss of these genes. As the first report of gram-negative bacteria incorporating cholesterol for survival, these findings offer insight into the unique nature of their parasitism and imply that cholesterol is important in the control of human ehrlichioses. | 2003 | 12933880 |
| 803 | 6 | 0.9352 | 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 |
| 161 | 7 | 0.9347 | Uniform designation for genes of the Calvin-Benson-Bassham reductive pentose phosphate pathway of bacteria. Structural and regulatory genes encoding enzymes and proteins of the reductive pentose phosphate pathway have been isolated from a number of bacteria recently. In the phototroph Rhodobacter sphaeroides, and in two chemoautotrophic bacteria, Alcaligenes eutrophus and Xanthobacter flavus, these genes have been found in distinct operons. However, in these three organisms and in other bacteria where certain of these genes have been discovered, a uniform nomenclature to designate these genes has been lacking. This report represents an effort to provide uniformity to the designation of these genes from all bacteria. | 1992 | 1490592 |
| 122 | 8 | 0.9345 | 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 |
| 491 | 9 | 0.9343 | Class II broad-spectrum mercury resistance transposons in Gram-positive bacteria from natural environments. We have studied the mechanisms of the horizontal dissemination of a broad-spectrum mercury resistance determinant among Bacillus and related species. This mer determinant was first described in Bacillus cereus RC607 from Boston Harbor, USA, and was then found in various Bacillus and related species in Japan, Russia and England. We have shown that the mer determinant can either be located at the chromosome, or on a plasmid in the Bacillus species, and is carried by class II mercury resistance transposons: Tn5084 from B. cereus RC607 and B. cereus VKM684 (ATCC10702) and Tn5085 from Exiguobacterium sp. TC38-2b. Tn5085 is identical in nucleotide sequence to TnMERI1, the only other known mer transposon from Bacillus species, but it does not contain an intron like TnMERI1. Tn5085 is functionally active in Escherichia coli. Tn5083, which we have isolated from B. megaterium MK64-1, contains an RC607-like mer determinant, that has lost some mercury resistance genes and possesses a merA gene which is a novel sequence variant that has not been previously described. Tn5083 and Tn5084 are recombinants, and are comprised of fragments from several transposons including Tn5085, and a relative of a putative transposon from B. firmus (which contains similar genes to the cadmium resistance operon of Staphylococcus aureus), as well as others. The sequence data showed evidence for recombination both between transposition genes and between mer determinants. | 2001 | 11446519 |
| 513 | 10 | 0.9340 | 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 |
| 115 | 11 | 0.9340 | Genome mining reveals uncommon alkylpyrones as type III PKS products from myxobacteria. Type III polyketide synthases (PKSs) are comparatively small homodimeric enzymes affording natural products with diverse structures and functions. While type III PKS biosynthetic pathways have been studied thoroughly in plants, their counterparts from bacteria and fungi are to date scarcely characterized. This gap is exemplified by myxobacteria from which no type III PKS-derived small molecule has previously been isolated. In this study, we conducted a genomic survey of myxobacterial type III PKSs and report the identification of uncommon alkylpyrones as the products of type III PKS biosynthesis from the myxobacterial model strain Myxococcus xanthus DK1622 through a self-resistance-guided screening approach focusing on genes encoding pentapetide repeat proteins, proficient to confer resistance to topoisomerase inhibitors. Using promoter-induced gene expression in the native host as well as heterologous expression of biosynthetic type III PKS genes, sufficient amounts of material could be obtained for structural elucidation and bioactivity testing, revealing potent topoisomerase activity in vitro. | 2019 | 30506464 |
| 6077 | 12 | 0.9339 | Brytella acorum gen. nov., sp. nov., a novel acetic acid bacterium from sour beverages. Polyphasic taxonomic and comparative genomic analyses revealed that a series of lambic beer isolates including strain LMG 32668(T) and the kombucha isolate LMG 32879 represent a novel species among the acetic acid bacteria, with Acidomonas methanolica as the nearest phylogenomic neighbor with a valid name. Overall genomic relatedness indices and phylogenomic and physiological analyses revealed that this novel species was best classified in a novel genus for which we propose the name Brytella acorum gen. nov., sp. nov., with LMG 32668(T) (=CECT 30723(T)) as the type strain. The B. acorum genomes encode a complete but modified tricarboxylic acid cycle, and complete pentose phosphate, pyruvate oxidation and gluconeogenesis pathways. The absence of 6-phosphofructokinase which rendered the glycolysis pathway non-functional, and an energy metabolism that included both aerobic respiration and oxidative fermentation are typical metabolic characteristics of acetic acid bacteria. Neither genome encodes nitrogen fixation or nitrate reduction genes, but both genomes encode genes for the biosynthesis of a broad range of amino acids. Antibiotic resistance genes or virulence factors are absent. | 2023 | 37429096 |
| 106 | 13 | 0.9339 | Genomic evidence of the illumination response mechanism and evolutionary history of magnetotactic bacteria within the Rhodospirillaceae family. BACKGROUND: Magnetotactic bacteria (MTB) are ubiquitous in natural aquatic environments. MTB can produce intracellular magnetic particles, navigate along geomagnetic field, and respond to light. However, the potential mechanism by which MTB respond to illumination and their evolutionary relationship with photosynthetic bacteria remain elusive. RESULTS: We utilized genomes of the well-sequenced genus Magnetospirillum, including the newly sequenced MTB strain Magnetospirillum sp. XM-1 to perform a comprehensive genomic comparison with phototrophic bacteria within the family Rhodospirillaceae regarding the illumination response mechanism. First, photoreceptor genes were identified in the genomes of both MTB and phototrophic bacteria in the Rhodospirillaceae family, but no photosynthesis genes were found in the MTB genomes. Most of the photoreceptor genes in the MTB genomes from this family encode phytochrome-domain photoreceptors that likely induce red/far-red light phototaxis. Second, illumination also causes damage within the cell, and in Rhodospirillaceae, both MTB and phototrophic bacteria possess complex but similar sets of response and repair genes, such as oxidative stress response, iron homeostasis and DNA repair system genes. Lastly, phylogenomic analysis showed that MTB cluster closely with phototrophic bacteria in this family. One photoheterotrophic genus, Phaeospirillum, clustered within and displays high genomic similarity with Magnetospirillum. Moreover, the phylogenetic tree topologies of magnetosome synthesis genes in MTB and photosynthesis genes in phototrophic bacteria from the Rhodospirillaceae family were reasonably congruent with the phylogenomic tree, suggesting that these two traits were most likely vertically transferred during the evolution of their lineages. CONCLUSION: Our new genomic data indicate that MTB and phototrophic bacteria within the family Rhodospirillaceae possess diversified photoreceptors that may be responsible for phototaxis. Their genomes also contain comprehensive stress response genes to mediate the negative effects caused by illumination. Based on phylogenetic studies, most of MTB and phototrophic bacteria in the Rhodospirillaceae family evolved vertically with magnetosome synthesis and photosynthesis genes. The ancestor of Rhodospirillaceae was likely a magnetotactic phototrophic bacteria, however, gain or loss of magnetotaxis and phototrophic abilities might have occurred during the evolution of ancestral Rhodospirillaceae lineages. | 2019 | 31117953 |
| 823 | 14 | 0.9336 | Characterization of the prtA and prtB genes of Erwinia chrysanthemi EC16. Two tandem metalloprotease-encoding structural genes, prtA and prtB, were sequenced from Erwinia chrysanthemi EC16. These were highly homologous to previously reported genes from the same bacteria, as well as to three other metalloprotease-encoding genes from enteric bacteria. The three tandem prt structural genes from strain EC16 were closely linked to a cluster of genes previously found to be essential for extracellular secretion of the metalloproteases. | 1993 | 8224883 |
| 176 | 15 | 0.9336 | The mercury resistance (mer) operon in a marine gliding flavobacterium, Tenacibaculum discolor 9A5. Genes conferring mercury resistance have been investigated in a variety of bacteria and archaea but not in bacteria of the phylum Bacteroidetes, despite their importance in many environments. We found, however, that a marine gliding Bacteroidetes species, Tenacibaculum discolor, was the predominant mercury-resistant bacterial taxon cultured from a salt marsh fertilized with mercury-contaminated sewage sludge. Here we report characterization of the mercuric reductase and the narrow-spectrum mercury resistance (mer) operon from one of these strains - T. discolor 9A5. This mer operon, which confers mercury resistance when cloned into Flavobacterium johnsoniae, encodes a novel mercury-responsive ArsR/SmtB family transcriptional regulator that appears to have evolved independently from other mercury-responsive regulators, a novel putative transport protein consisting of a fusion between the integral membrane Hg(II) transporter MerT and the periplasmic Hg(II)-binding protein MerP, an additional MerP protein, and a mercuric reductase that is phylogenetically distinct from other known mercuric reductases. | 2013 | 22816663 |
| 6199 | 16 | 0.9332 | A bacterial gene homologous to ABC transporters protect Oenococcus oeni from ethanol and other stress factors in wine. The wine lactic acid bacteria Oenococcus oeni has to cope with harsh environmental conditions including an acidic pH, a high alcoholic content, non-optimal growth temperatures, and growth inhibitory compounds such as fatty acids, phenolic acids and tannins. We here describe characterisation and cloning of the O. oeni omrA gene encoding a protein belonging to the ATP-binding cassette superfamily of transporters. The OmrA protein displays the highest sequence similarity with the subfamily of ATP-dependent multidrug resistance (MDR) proteins, most notably the bacterial Lactococcus lactis LmrA homologue of the human MDR1 P-glycoprotein. The omrA gene proved to be a stress-responsive gene since its expression was increased at high temperature or under osmotic shock. The OmrA protein function was tested in Escherichia coli, and consistent with the omrA gene expression pattern, OmrA conferred protection to bacteria grown on a high salt medium. OmrA also triggered bacterial resistance to sodium laurate, wine and ethanol toxicity. The homologous LmrA protein featured the same stress-protective pattern than OmrA when expressed in E. coli, and the contribution to resistance of both OmrA and LmrA transporters was decreased by verapamil, a well-known inhibitor of the human MDR1 protein. Genes homologous to omrA were detected in other wine lactic acid bacteria, suggesting that this type of genes might constitute a well-conserved stress-protective molecular device. | 2004 | 15033264 |
| 104 | 17 | 0.9331 | Bile Salt Hydrolases with Extended Substrate Specificity Confer a High Level of Resistance to Bile Toxicity on Atopobiaceae Bacteria. The bile resistance of intestinal bacteria is among the key factors responsible for their successful colonization of and survival in the mammalian gastrointestinal tract. In this study, we demonstrated that lactate-producing Atopobiaceae bacteria (Leptogranulimonas caecicola TOC12(T) and Granulimonas faecalis OPF53(T)) isolated from mouse intestine showed high resistance to mammalian bile extracts, due to significant bile salt hydrolase (BSH) activity. We further succeeded in isolating BSH proteins (designated LcBSH and GfBSH) from L. caecicola TOC12(T) and G. faecalis OPF53(T), respectively, and characterized their enzymatic features. Interestingly, recombinant LcBSH and GfBSH proteins exhibited BSH activity against 12 conjugated bile salts, indicating that LcBSH and GfBSH have much broader substrate specificity than the previously identified BSHs from lactic acid bacteria, which are generally known to hydrolyze six bile salt isomers. Phylogenetic analysis showed that LcBSH and GfBSH had no affinities with any known BSH subgroup and constituted a new BSH subgroup in the phylogeny. In summary, we discovered functional BSHs with broad substrate specificity from Atopobiaceae bacteria and demonstrated that these BSH enzymes confer bile resistance to L. caecicola TOC12(T) and G. faecalis OPF53(T). | 2022 | 36142891 |
| 6133 | 18 | 0.9330 | Comparative genomic study of three species within the genus Ornithinibacillus, reflecting the adaption to different habitats. In the present study, we report the whole genome sequences of two species, Ornithinibacillus contaminans DSM22953(T) isolated from human blood and Ornithinibacillus californiensis DSM 16628(T) isolated from marine sediment, in genus Ornithinibacillus. Comparative genomic study of the two species was conducted together with their close relative Ornithinibacillus scapharcae TW25(T), a putative pathogenic bacteria isolated from dead ark clam. The comparisons showed O. contaminans DSM22953(T) had the smallest genome size of the three species indicating that it has a relatively more stable habitat. More stress response and heavy metal resistance genes were found in the genome of O. californiensis DSM 16628(T) reflecting its adaption to the complex marine environment. O. scapharcae TW25(T) contained more antibiotic resistance genes and virus factors in the genome than the other two species, which revealed its pathogen potential. | 2016 | 26706221 |
| 192 | 19 | 0.9330 | N-Succinyltransferase Encoded by a Cryptic Siderophore Biosynthesis Gene Cluster in Streptomyces Modifies Structurally Distinct Antibiotics. The antibiotic desertomycin A and its previously undescribed inactive N-succinylated analogue, desertomycin X, were isolated from Streptomyces sp. strain YIM 121038. Genome sequencing and analysis readily identified the desertomycin biosynthetic gene cluster (BGC), which lacked genes encoding acyltransferases that would account for desertomycin X formation. Scouting the genome for putative N-acyltransferase genes led to the identification of a candidate within a cryptic siderophore BGC (csb) encoding a putative homologue of the N6'-hydroxylysine acetyltransferase IucB. Expression of the codon-optimized gene designated csbC in Escherichia coli yielded the recombinant protein that was able to N-succinylate desertomycin A as well as several other structurally distinct antibiotics harboring amino groups. Some antibiotics were rendered antibiotically inactive due to the CsbC-catalyzed succinylation in vitro. Unlike many known N-acyltransferases involved in antibiotic resistance, CsbC could not efficiently acetylate the same antibiotics. When expressed in E. coli, CsbC provided low-level resistance to kanamycin and ampicillin, suggesting that it may play a role in antibiotic resistance in natural habitats, where the concentration of antibiotics is usually low. IMPORTANCE In their natural habitats, bacteria encounter a plethora of organic compounds, some of which may be represented by antibiotics produced by certain members of the microbial community. A number of antibiotic resistance mechanisms have been described, including those specified by distinct genes encoding proteins that degrade, modify, or expel antibiotics. In this study, we report identification and characterization of an enzyme apparently involved in the biosynthesis of a siderophore, but also having the ability of modify and thereby inactivate a wide variety of structurally diverse antibiotics. This discovery sheds light on additional capabilities of bacteria to withstand antibiotic treatment and suggests that enzymes involved in secondary metabolism may have an additional function in the natural environment. | 2022 | 36040031 |