title: Involvement of the arginine repressor in lysine biosynthesis of Thermus thermophilus.
abstract: Lysine biosynthesis of Thermus thermophilus proceeds in a similar way to arginine biosynthesis, and some lysine biosynthetic enzymes from T. thermophilus so far investigated have the potential to function in arginine biosynthesis. These observations suggest that arginine might regulate the expression of genes for lysine biosynthesis. To test this hypothesis, the argR gene encoding the regulator of arginine biosynthesis was cloned from T. thermophilus and its function in lysine biosynthesis was analysed. The addition of arginine to the culture medium inhibited the growth of an arginase gene knockout mutant of T. thermophilus, which presumably accumulates arginine inside the cells. Arginine-dependent growth inhibition was not alleviated by the addition of ornithine, which is a biosynthetic intermediate of arginine and serves as a peptidoglycan component of the cell wall in T. thermophilus. However, the growth inhibition was cancelled either by the simultaneous addition of lysine and ornithine or by a knockout of the argR gene, suggesting the involvement of argR in regulation of lysine biosynthesis in T. thermophilus. Electrophoretic mobility shift assay and DNase I footprinting revealed that the ArgR protein specifically binds to the promoter region of the major lysine biosynthetic gene cluster. Furthermore, an alpha-galactosidase reporter assay for this promoter indicated that arginine repressed the promoter in an argR-dependent manner. These results indicate that lysine biosynthesis is regulated by arginine in T. thermophilus.
authors.affiliation: Biotechnology Research Center, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Biotechnology Research Center, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Taishi
authors.initials: T
authors.lastname: Tsubouchi
authors.affiliation: Biotechnology Research Center, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Kuzuyama
authors.affiliation: RIKEN Spring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.|Biotechnology Research Center, the University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishiyama
mesh_terms: D001119:Arginase / Q000235:genetics; D001120:Arginine / Q000378:metabolism; D001426:Bacterial Proteins / Q000502:physiology*; D018983:DNA Footprinting; D004269:DNA, Bacterial / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008239:Lysine / Q000096:biosynthesis*; D009952:Ornithine / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000502:physiology*; D016963:Thermus thermophilus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D000519:alpha-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: C087018:ArgR protein, Bacteria; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012097:Repressor Proteins; D001120:Arginine; D009952:Ornithine; D000519:alpha-Galactosidase; D001119:Arginase; D008239:Lysine