title: Functional diversity of five homologous Cu+-ATPases present in Sinorhizobium meliloti.
abstract: Copper is an important element in host-microbe interactions, acting both as a catalyst in enzymes and as a potential toxin. Cu(+)-ATPases drive cytoplasmic Cu(+) efflux and protect bacteria against metal overload. Many pathogenic and symbiotic bacteria contain multiple Cu(+)-ATPase genes within particular genetic environments, suggesting alternative roles for each resulting protein. This hypothesis was tested by characterizing five homologous Cu(+)-ATPases present in the symbiotic organism Sinorhizobium meliloti. Mutation of each gene led to different phenotypes and abnormal nodule development in the alfalfa host. Distinct responses were detected in free-living S. meliloti mutant strains exposed to metal and redox stresses. Differential gene expression was detected under Cu(+), oxygen or nitrosative stress. These observations suggest that CopA1a maintains the cytoplasmic Cu(+) quota and its expression is controlled by Cu(+) levels. CopA1b is also regulated by Cu(+) concentrations and is required during symbiosis for bacteroid maturation. CopA2-like proteins, FixI1 and FixI2, are necessary for the assembly of two different cytochrome c oxidases at different stages of bacterial life. CopA3 is a phylogenetically distinct Cu(+)-ATPase that does not contribute to Cu(+) tolerance. It is regulated by redox stress and required during symbiosis. We postulated a model where non-redundant homologous Cu(+)-ATPases, operating under distinct regulation, transport Cu(+) to different target proteins.
authors.affiliation: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
authors.forename: Sarju J
authors.initials: SJ
authors.lastname: Patel
authors.affiliation: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
authors.forename: Teresita
authors.initials: T
authors.lastname: Padilla-Benavides
authors.affiliation: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Collins
authors.affiliation: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.
authors.forename: José M
authors.initials: JM
authors.lastname: Argüello
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D055786:Gene Knockout Techniques; D000455:Medicago sativa / Q000382:microbiology; D008670:Metals / Q000378:metabolism / Q000633:toxicity; D009603:Nitroso Compounds / Q000378:metabolism / Q000633:toxicity; D016877:Oxidants / Q000378:metabolism / Q000633:toxicity; D055170:Plant Root Nodulation; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D013312:Stress, Physiological
chemical_list: D027682:Cation Transport Proteins; D008670:Metals; D009603:Nitroso Compounds; D016877:Oxidants; D000251:Adenosine Triphosphatases; D000073840:Copper-Transporting ATPases