title: Pleiotropic effects of mutations that alter the Sinorhizobium meliloti cytochrome c respiratory system.
abstract: Using transposon mutagenesis, mutations have been isolated in several genes (ccdA, cycM, ccmC, ccmB and senC) that play a role in Sinorhizobium meliloti cytochrome metabolism. As in other bacteria, mutations in the S. meliloti ccdA, ccmB and ccmC genes resulted in the absence of all c-type cytochromes. However, the S. meliloti ccdA mutant also lacked cytochrome oxidase aa(3), a defect that does not appear to have been reported for other bacteria. The aa(3)-type cytochromes were also missing from a mutant strain with an insertion into the gene encoding the haem-containing subunit (SU)I of aa(3) cytochrome c oxidase, but not in mutants unable to make SUII or SUIII, indicating that CcdA probably plays a role in assembling SUI. The cytochrome-deficient mutants also had other free-living phenotypes, including a significant decrease in growth rate on rich media and increased motility on minimal media. A senC mutant also had significantly decreased motility, but the motility and growth properties of the cycM mutant were unchanged. Unlike similar mutants in Bradyrhizobium japonicum and Rhizobium leguminosarum, an S. meliloti Rm1021 cycM mutant contained cytochrome oxidase aa(3). Cytochrome maturation in strain Rm1021 appeared to be similar to maturation in other rhizobia, but there were some differences in the cytochrome composition of the strain, and respiration chain function and assembly.
authors.affiliation: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Svetlana N
authors.initials: SN
authors.lastname: Yurgel
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Jhoanna
authors.initials: J
authors.lastname: Berrocal
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Wilson
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6340, USA.|Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Kahn
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009154:Mutation; D010101:Oxygen Consumption / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C068355:CcdA protein, Bacteria; C116246:CcmC protein, bacteria; D003574:Cytochrome c Group; D004251:DNA Transposable Elements; D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins