title: Copper resistance and its regulation in the sulfate-reducing bacteriumDesulfosporosinussp. OT.
abstract: Desulfosporosinussp. OT is a Gram-positive, acidophilic sulfate-reducing firmicute isolated from copper tailings sediment in the Norilsk mining-smelting area in Siberia and represents the firstDesulfosporosinusspecies whose genome has been sequenced.Desulfosporosinussp. OT is exceptionally copper resistant, which made it of interest to study the resistance mechanism. It possesses acopUAZoperon which is shown here to be involved in copper resistance. ThecopUgene encodes a CsoR-type homotetrameric repressor. By electrophoretic mobility shift assay, it was shown that CopU binds to the operator/promoter region of thecopUAZoperon in the absence of copper and is released from the DNA by Cu+or Ag+, implying that CopU regulates the operon in a copper/silver-dependent manner. DOT_CopA is a P1B-type ATPase related to other characterized, bacterial copper ATPases. When expressed in a copper-sensitiveEscherichia coliΔcopAmutant, it restores copper resistance to WT levels. His-tagged DOT_CopA was expressed from a plasmid inE. coliand purified by Ni-NTA affinity chromatography. The purified enzyme was most active in the presence of Cu(I) and bacterial phospholipids. These findings indicate that thecopUAZoperon confers copper resistance toDesulfosporosinussp. OT, but do not per se explain the basis of the high copper resistance of this strain.
authors.affiliation: Department of Clinical Research, University of Bern, 3010 Bern, Switzerland.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mancini
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Tomsk State University, 634050 Tomsk, Russia.
authors.forename: Ranjeet
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Department of Clinical Research, University of Bern, 3010 Bern, Switzerland.
authors.forename: Helge K
authors.initials: HK
authors.lastname: Abicht
authors.affiliation: Department of Clinical Research, University of Bern, 3010 Bern, Switzerland.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fischermeier
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Tomsk State University, 634050 Tomsk, Russia.|Department of Clinical Research, University of Bern, 3010 Bern, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Solioz