Tn5041-like transposons: molecular diversity, evolutionary relationships and distribution of distinct variants in environmental bacteria b bThe accession numbers for the nucleotide sequences reported in this work are given in the legends for Figs 1 F1 and 2. c cA comparison of the sequence of INT5041C with other proteins is available as supplementary data on Microbiology Online (http://mic.sgmjournals.org).

Kholodii, Gennady; Gorlenko, Zh. M.; Mindlin, S. Z.; Hobman, Jonathan L.; Nikiforov, Vadim

doi:10.1099/00221287-148-11-3569

Cited by 29 publications

(32 citation statements)

References 48 publications

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“…Phylogenetic analysis of the deduced amino acid sequences (Fig. 2) revealed that the genes from the moderate thermophiles (strains EPR6, EPR7, and EPR8) formed a unique cluster that was most closely related to, yet distinct from, the clade that includes the best-characterized MR (17). While closely related, the MerA fragments of these Alcanivorax strains differed from each other by one to three amino acid residues.…”

Section: Resultsmentioning

confidence: 99%

“…The broadly distributed bacterial mercury resistance (mer) operon encodes a flavoenzyme, mercuric reductase (MR), that reduces ionic mercury [Hg(II)] to the elemental, less toxic form [Hg(0)], which then partitions into the vapor phase at the solid-gas and liquid-gas interfaces (6). In highly contaminated surficial environments, bacteria that possess (17) and express (30) the MR gene, merA, are enriched, and their activities enhance the removal of mercury, thereby decreasing its burden to the ecosystem (4). In the present study we found high levels of merA-specified resistance to Hg(II) in bacteria isolated from the interface between hydrothermal fluids and oxygenated seawater, and in this paper we report that MR from a mesophilic bacterium is a thermophilic enzyme.…”

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confidence: 99%

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Mercury Adaptation among Bacteria from a Deep-Sea Hydrothermal Vent

Vetriani

Chew²,

Miller

et al. 2005

Appl Environ Microbiol

114

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Since deep-sea hydrothermal vent fluids are enriched with toxic metals, it was hypothesized that (i) the biota in the vicinity of a vent is adapted to life in the presence of toxic metals and (ii) metal toxicity is modulated by the steep physical-chemical gradients that occur when anoxic, hot fluids are mixed with cold oxygenated seawater. We collected bacterial biomass at different distances from a diffuse flow vent at 9°N on the East Pacific Rise and tested these hypotheses by examining the effect of mercuric mercury [Hg(II)] on vent bacteria. Four of six moderate thermophiles, most of which were vent isolates belonging to the genus Alcanivorax, and six of eight mesophiles from the vent plume were resistant to >10 M Hg(II) and reduced it to elemental mercury [Hg(0)]. However, four psychrophiles that were isolated from a nearby inactive sulfide structure were Hg(II) sensitive. A neighbor-joining tree constructed from the deduced amino acids of a PCR-amplified fragment of merA, the gene encoding the mercuric reductase (MR), showed that sequences obtained from the vent moderate thermophiles formed a unique cluster (bootstrap value, 100) in the MR phylogenetic tree, which expanded the known diversity of this locus. The temperature optimum for Hg(II) reduction by resting cells and MR activity in crude cell extracts of a vent moderate thermophile corresponded to its optimal growth temperature, 45°C. However, the optimal temperature for activity of the MR encoded by transposon Tn501 was found to be 55 to 65°C, suggesting that, in spite of its original isolation from a mesophile, this MR is a thermophilic enzyme that may represent a relic of early evolution in high-temperature environments. Results showing that there is enrichment of Hg(II) resistance among vent bacteria suggest that these bacteria have an ecological role in mercury detoxification in the vent environment and, together with the thermophilicity of MR, point to geothermal environments as a likely niche for the evolution of bacterial mercury resistance.Heavy metals are highly enriched in hydrothermal vent fluids of mid-oceanic ridge systems (35), reaching concentrations that are considered to be toxic to living organisms (26). The steep physical-chemical gradients that occur when reduced, hot, element-and sulfur-rich vent fluids are diluted with oxygenated, cold seawater create a gradient in metal toxicity in the vent environment (20). As oxygen mixes with the anoxic, sulfur-rich fluid, metal speciation can shift from metal sulfides that show poor bioavailability and low toxicity to more soluble and oxidized forms with increased bioavailability and toxicity. With such a change in metal speciation, high tolerance to metals is expected among microbes inhabiting niches of the vent ecosystem where mixing between hydrothermal fluids and oxygenated seawater occurs, such as diffuse flow vents and associated plumes. This hypothesis is supported by experimental data showing that thermophilic archaea and bacteria from highly reduced vent microhabitats were metal su...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Mercury Adaptation among Bacteria from a Deep-Sea Hydrothermal Vent

Vetriani

Chew²,

Miller

et al. 2005

Appl Environ Microbiol

114

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“…strain LS46-6 (52), and Tn5041 from another Pseudomonas sp. (53,54). Since the mer operon is Tn5044-like rather than Tn21-like, and the tniA gene is truncated, it suggests that Tn21, with or without the potentially transposable tniABQR-type integron already in its res site, arrived in pOZ176 first, followed by the Tn5044-like element, whose 38-bp transposon end is found at the point of truncation of tniA.…”

Section: Discussionmentioning

confidence: 99%

Complete Sequence of pOZ176, a 500-Kilobase IncP-2 Plasmid Encoding IMP-9-Mediated Carbapenem Resistance, from Outbreak Isolate Pseudomonas aeruginosa 96

Xiong

Alexander

Jennifer

et al. 2013

Antimicrob Agents Chemother

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Pseudomonas aeruginosa 96 (PA96) was isolated during a multicenter surveillance study in Guangzhou, China, in 2000. Wholegenome sequencing of this outbreak strain facilitated analysis of its IncP-2 carbapenem-resistant plasmid, pOZ176. The plasmid had a length of 500,839 bp and an average percent G؉C content of 57%. Of the 618 predicted open reading frames, 65% encode hypothetical proteins. The pOZ176 backbone is not closely related to any plasmids thus far sequenced, but some similarity to pQBR103 of Pseudomonas fluorescens SBW25 was observed. Two multiresistant class 1 integrons and several insertion sequences were identified. The bla IMP-9 -carrying integron contained aacA4¡bla IMP-9 ¡aacA4, flanked upstream by Tn21 tnpMRA and downstream by a complete tni operon of Tn402 and a mer module, named Tn6016. The second integron carried aacA4¡catB8a¡bla OXA-10 and was flanked by Tn1403-like tnpRA and a sul1-type 3= conserved sequence (3=-CS), named Tn6217. Other features include three resistance genes similar to those of Tn5, a tellurite resistance operon, and two pil operons. The replication and maintenance systems exhibit similarity to a genomic island of Ralstonia solanacearum GM1000. Codon usage analysis suggests the recent acquisition of bla IMP-9 . The origins of the integrons on pOZ176 indicated separate horizontal gene transfer events driven by antibiotic selection. The novel mosaic structure of pOZ176 suggests that it is derived from environmental bacteria.

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“…1C) is highly similar to Tn 5058 in Pseudomonas sp. ED23-33 [55]. The length of both sequences are 12, 373 bp and the nucleotide similarity varies from 96 to 99% except for the first 257 bp where similarity is 84%, but the IR at the start of the element again has a perfect match with Tn 5058 .…”

Section: Resultsmentioning

confidence: 99%

“…Tn 5058 has two copies of merR, merB and merD . Interestingly, it was suggested that the duplications in some of the mer genes in Tn 5041D were the result of an integration, via homologous recombination, of a mer containing circular DNA structure [55]. The circular cassette was speculated to originate from an ancestral donor in which the mer genes were flanked by IS elements.…”

Section: Resultsmentioning

confidence: 99%

Complete Nucleotide Sequence and Analysis of Two Conjugative Broad Host Range Plasmids from a Marine Microbial Biofilm

2014

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The complete nucleotide sequence of plasmids pMCBF1 and pMCBF6 was determined and analyzed. pMCBF1 and pMCBF6 form a novel clade within the IncP-1 plasmid family designated IncP-1 ς. The plasmids were exogenously isolated earlier from a marine biofilm. pMCBF1 (62 689 base pairs; bp) and pMCBF6 (66 729 bp) have identical backbones, but differ in their mercury resistance transposons. pMCBF1 carries Tn5053 and pMCBF6 carries Tn5058. Both are flanked by 5 bp direct repeats, typical of replicative transposition. Both insertions are in the vicinity of a resolvase gene in the backbone, supporting the idea that both transposons are “res-site hunters” that preferably insert close to and use external resolvase functions. The similarity of the backbones indicates recent insertion of the two transposons and the ongoing dynamics of plasmid evolution in marine biofilms. Both plasmids also carry the insertion sequence ISPst1, albeit without flanking repeats. ISPs1is located in an unusual site within the control region of the plasmid. In contrast to most known IncP-1 plasmids the pMCBF1/pMCBF6 backbone has no insert between the replication initiation gene (trfA) and the vegetative replication origin (oriV). One pMCBF1/pMCBF6 block of about 2.5 kilo bases (kb) has no similarity with known sequences in the databases. Furthermore, insertion of three genes with similarity to the multidrug efflux pump operon mexEF and a gene from the NodT family of the tripartite multi-drug resistance-nodulation-division (RND) system in Pseudomonas aeruginosa was found. They do not seem to confer antibiotic resistance to the hosts of pMCBF1/pMCBF6, but the presence of RND on promiscuous plasmids may have serious implications for the spread of antibiotic multi-resistance.

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Cited by 29 publications

References 48 publications

Mercury Adaptation among Bacteria from a Deep-Sea Hydrothermal Vent

Mercury Adaptation among Bacteria from a Deep-Sea Hydrothermal Vent

Complete Sequence of pOZ176, a 500-Kilobase IncP-2 Plasmid Encoding IMP-9-Mediated Carbapenem Resistance, from Outbreak Isolate Pseudomonas aeruginosa 96

Complete Nucleotide Sequence and Analysis of Two Conjugative Broad Host Range Plasmids from a Marine Microbial Biofilm

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