ABSTRACTMicrobial transformations of arsenic influence its mobility and toxicity. We report the d... more ABSTRACTMicrobial transformations of arsenic influence its mobility and toxicity. We report the draft genome sequence of the arsenite-oxidizing strainAgrobacterium tumefaciens5A isolated from an As-contaminated soil in the Madison River Valley, MT. A large number of metal (or metalloid) resistance genes, especially contributing to arsenite oxidation, were identified.
We present the draft genome sequence of Pseudomonas stutzeri TS44, a moderately halotolerant, ars... more We present the draft genome sequence of Pseudomonas stutzeri TS44, a moderately halotolerant, arsenite-oxidizing bacterium isolated from arsenic-contaminated soil. The genome contains genes for arsenite oxidation, arsenic resistance, and ectoine/hydroxyectoine biosynthesis. The genome information will be useful for exploring adaptation of P. stutzeri TS44 to an arsenic-contaminated environment.
Cadmium and zinc are removed from cells of Ralstonia metallidurans by the CzcCBA efflux pump and ... more Cadmium and zinc are removed from cells of Ralstonia metallidurans by the CzcCBA efflux pump and by two soft-metal-transporting P-type ATPases, CadA and ZntA. The czcCBA genes are located on plasmid pMOL30, and the cadA and zntA genes are on the bacterial chromosome. Expression of zntA from R . metallidurans in Escherichia coli predominantly mediated resistance to zinc, and expression of cadA predominantly mediated resistance to cadmium. Both transporters decreased the cellular content of zinc or cadmium in this host. In the plasmid-free R . metallidurans strain AE104, single gene deletions of cadA or zntA had only a moderate effect on cadmium and zinc resistance, but zinc resistance decreased 6-fold and cadmium resistance decreased 350-fold in double deletion strains. Neither single nor double gene deletions affected zinc resistance in the presence of czcCBA . In contrast, cadmium resistance of the cadA zntA double mutant could be elevated only partially by the presence of CzcCBA. ...
In this study with the model organism Agrobacterium tumefaciens , we used a combination of lacZ g... more In this study with the model organism Agrobacterium tumefaciens , we used a combination of lacZ gene fusions, reverse transcriptase PCR (RT-PCR), and deletion and insertional inactivation mutations to show unambiguously that the alternative sigma factor RpoN participates in the regulation of As III oxidation. A deletion mutation that removed the RpoN binding site from the aioBA promoter and an aacC3 (gentamicin resistance) cassette insertional inactivation of the rpoN coding region eliminated aioBA expression and As III oxidation, although rpoN expression was not related to cell exposure to As III . Putative RpoN binding sites were identified throughout the genome and, as examples, included promoters for aioB , phoB1 , pstS1 , dctA , glnA , glnB , and flgB that were examined by using qualitative RT-PCR and lacZ reporter fusions to assess the relative contribution of RpoN to their transcription. The expressions of aioB and dctA in the wild-type strain were considerably enhanced in ce...
Proceedings of the National Academy of Sciences, 2000
The copA gene product, a putative copper-translocating P-type ATPase, has been shown to be involv... more The copA gene product, a putative copper-translocating P-type ATPase, has been shown to be involved in copper resistance in Escherichia coli . The copA gene was disrupted by insertion of a kanamycin gene through homologous recombination. The mutant strain was more sensitive to copper salts but not to salts of other metals, suggesting a role in copper homeostasis. The copper-sensitive phenotype could be rescued by complementation by a plasmid carrying copA from E. coli or copB from Enterococcus hirae . Expression of copA was induced by salts of copper or silver but not zinc or cobalt. Everted membrane vesicles from cells expressing copA exhibited ATP-coupled accumulation of copper, presumably as Cu(I). The results indicate that CopA is a Cu(I)-translocating efflux pump that is similar to the copper pumps related to Menkes and Wilson diseases and provides a useful prokaryotic model for these human diseases.
Archaea have been discovered in non-extreme environments recently but not in Chinese pristine soi... more Archaea have been discovered in non-extreme environments recently but not in Chinese pristine soils so far. This study was conducted to assess the presence of Archaea in two Asian pristine soils from Xinjiang and Guangxi of China and in two North American soils ...
The membrane-bound CzcCBA protein complex mediates heavy metal resistance in Alcaligenes eutrophu... more The membrane-bound CzcCBA protein complex mediates heavy metal resistance in Alcaligenes eutrophus by an active cation efflux mechanism driven by cation-proton antiport. The CzcA protein alone is able to mediate weak resistance to zinc and cobalt and is thus the central antiporter subunit. The two histidine-rich motifs in the CzcB subunit are not essential for zinc resistance; however, deletion of both motifs led to a small but significant loss of resistance to this cation. Translation of the czcC gene encoding the third subunit of the CzcCBA complex starts earlier than predicted, and CzcC is probably a periplasmic protein, as judged by the appearance of two bands after expression of czcC in Escherichia coli under control of the phage T7 promoter. Fusions of CzcC and CzcB with alkaline phosphatase and beta-galactosidase are in agreement with a periplasmic location of most parts of both proteins. Both CzcC and CzcB are bound to a membrane, probably the outer membrane, by themselves a...
ABSTRACTMicrobial transformations of arsenic influence its mobility and toxicity. We report the d... more ABSTRACTMicrobial transformations of arsenic influence its mobility and toxicity. We report the draft genome sequence of the arsenite-oxidizing strainAgrobacterium tumefaciens5A isolated from an As-contaminated soil in the Madison River Valley, MT. A large number of metal (or metalloid) resistance genes, especially contributing to arsenite oxidation, were identified.
We present the draft genome sequence of Pseudomonas stutzeri TS44, a moderately halotolerant, ars... more We present the draft genome sequence of Pseudomonas stutzeri TS44, a moderately halotolerant, arsenite-oxidizing bacterium isolated from arsenic-contaminated soil. The genome contains genes for arsenite oxidation, arsenic resistance, and ectoine/hydroxyectoine biosynthesis. The genome information will be useful for exploring adaptation of P. stutzeri TS44 to an arsenic-contaminated environment.
Cadmium and zinc are removed from cells of Ralstonia metallidurans by the CzcCBA efflux pump and ... more Cadmium and zinc are removed from cells of Ralstonia metallidurans by the CzcCBA efflux pump and by two soft-metal-transporting P-type ATPases, CadA and ZntA. The czcCBA genes are located on plasmid pMOL30, and the cadA and zntA genes are on the bacterial chromosome. Expression of zntA from R . metallidurans in Escherichia coli predominantly mediated resistance to zinc, and expression of cadA predominantly mediated resistance to cadmium. Both transporters decreased the cellular content of zinc or cadmium in this host. In the plasmid-free R . metallidurans strain AE104, single gene deletions of cadA or zntA had only a moderate effect on cadmium and zinc resistance, but zinc resistance decreased 6-fold and cadmium resistance decreased 350-fold in double deletion strains. Neither single nor double gene deletions affected zinc resistance in the presence of czcCBA . In contrast, cadmium resistance of the cadA zntA double mutant could be elevated only partially by the presence of CzcCBA. ...
In this study with the model organism Agrobacterium tumefaciens , we used a combination of lacZ g... more In this study with the model organism Agrobacterium tumefaciens , we used a combination of lacZ gene fusions, reverse transcriptase PCR (RT-PCR), and deletion and insertional inactivation mutations to show unambiguously that the alternative sigma factor RpoN participates in the regulation of As III oxidation. A deletion mutation that removed the RpoN binding site from the aioBA promoter and an aacC3 (gentamicin resistance) cassette insertional inactivation of the rpoN coding region eliminated aioBA expression and As III oxidation, although rpoN expression was not related to cell exposure to As III . Putative RpoN binding sites were identified throughout the genome and, as examples, included promoters for aioB , phoB1 , pstS1 , dctA , glnA , glnB , and flgB that were examined by using qualitative RT-PCR and lacZ reporter fusions to assess the relative contribution of RpoN to their transcription. The expressions of aioB and dctA in the wild-type strain were considerably enhanced in ce...
Proceedings of the National Academy of Sciences, 2000
The copA gene product, a putative copper-translocating P-type ATPase, has been shown to be involv... more The copA gene product, a putative copper-translocating P-type ATPase, has been shown to be involved in copper resistance in Escherichia coli . The copA gene was disrupted by insertion of a kanamycin gene through homologous recombination. The mutant strain was more sensitive to copper salts but not to salts of other metals, suggesting a role in copper homeostasis. The copper-sensitive phenotype could be rescued by complementation by a plasmid carrying copA from E. coli or copB from Enterococcus hirae . Expression of copA was induced by salts of copper or silver but not zinc or cobalt. Everted membrane vesicles from cells expressing copA exhibited ATP-coupled accumulation of copper, presumably as Cu(I). The results indicate that CopA is a Cu(I)-translocating efflux pump that is similar to the copper pumps related to Menkes and Wilson diseases and provides a useful prokaryotic model for these human diseases.
Archaea have been discovered in non-extreme environments recently but not in Chinese pristine soi... more Archaea have been discovered in non-extreme environments recently but not in Chinese pristine soils so far. This study was conducted to assess the presence of Archaea in two Asian pristine soils from Xinjiang and Guangxi of China and in two North American soils ...
The membrane-bound CzcCBA protein complex mediates heavy metal resistance in Alcaligenes eutrophu... more The membrane-bound CzcCBA protein complex mediates heavy metal resistance in Alcaligenes eutrophus by an active cation efflux mechanism driven by cation-proton antiport. The CzcA protein alone is able to mediate weak resistance to zinc and cobalt and is thus the central antiporter subunit. The two histidine-rich motifs in the CzcB subunit are not essential for zinc resistance; however, deletion of both motifs led to a small but significant loss of resistance to this cation. Translation of the czcC gene encoding the third subunit of the CzcCBA complex starts earlier than predicted, and CzcC is probably a periplasmic protein, as judged by the appearance of two bands after expression of czcC in Escherichia coli under control of the phage T7 promoter. Fusions of CzcC and CzcB with alkaline phosphatase and beta-galactosidase are in agreement with a periplasmic location of most parts of both proteins. Both CzcC and CzcB are bound to a membrane, probably the outer membrane, by themselves a...
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