title: Growth Rate of and Gene Expression in Bradyrhizobium diazoefficiens USDA110 due to a Mutation in blr7984, a TetR Family Transcriptional Regulator Gene.
abstract: Previous transcriptome analyses have suggested that a gene cluster including a transcriptional regulator (blr7984) of the tetracycline repressor family was markedly down-regulated in symbiosis. Since blr7984 is annotated to be the transcriptional repressor, we hypothesized that it is involved in the repression of genes in the genomic cluster including blr7984 in symbiotic bacteroids. In order to examine the function and involvement of the blr7984 gene in differentiation into bacteroids, we compared the free-living growth/symbiotic phenotype and gene expression between a blr7984-knockout mutant and the wild-type strain of Bradyrhizobium diazoefficiens USDA110. The mutant transiently increased the cell growth rate under free-living conditions and nodule numbers over those with the wild-type strain USDA110. The expression of three genes adjacent to the disrupted blr7984 gene was strongly up-regulated in the mutant in free-living and symbiotic cells. The mutant also induced the expression of genes for glutathione S-transferase, cytochrome c oxidases, ABC transporters, PTS sugar transport systems, and flagella synthesis under free-living conditions. bll7983 encoding glutathione S-transferase was up-regulated the most by the blr7984 disruption. Since redox regulation by glutathione is known to be involved in cell division in prokaryotes and eukaryotes, the strong expression of glutathione S-transferase encoded by the bll7983 gene may have caused redox changes in mutant cells, which resulted in higher rates of cell division.
authors.affiliation: Institute of Agriculture, Tokyo University of Agriculture and Technology.
authors.forename: Naoko
authors.initials: N
authors.lastname: Ohkama-Ohtsu
authors.forename: Haruna
authors.initials: H
authors.lastname: Honma
authors.forename: Mariko
authors.initials: M
authors.lastname: Nakagome
authors.forename: Maki
authors.initials: M
authors.lastname: Nagata
authors.forename: Hiroko
authors.initials: H
authors.lastname: Yamaya-Ito
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Sano
authors.forename: Norina
authors.initials: N
authors.lastname: Hiraoka
authors.forename: Takaaki
authors.initials: T
authors.lastname: Ikemi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Suzuki
authors.forename: Shin
authors.initials: S
authors.lastname: Okazaki
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Minamisawa
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yokoyama
mesh_terms: D018441:Biofilms / Q000254:growth & development; D020369:Bradyrhizobium / Q000235:genetics* / Q000254:growth & development* / Q000502:physiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005809:Genes, Regulator; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics*
chemical_list: D012097:Repressor Proteins