title: Protein acetylation involved in streptomycin biosynthesis in Streptomyces griseus.
abstract: Protein acetylation, the reversible addition of an acetyl group to lysine residues, is a protein post-translational modification ubiquitous in living cells. Although the involvement of protein acetylation in the regulation of primary metabolism has been revealed, the function of protein acetylation is largely unknown in secondary metabolism. Here, we characterized protein acetylation in Streptomyces griseus, a streptomycin producer. Protein acetylation was induced in the stationary and sporulation phases in liquid and solid cultures, respectively, in S. griseus. By comprehensive acetylome analysis, we identified 134 acetylated proteins with 162 specific acetylated sites. Acetylation was found in proteins related to primary metabolism and translation, as in other bacteria. However, StrM, a deoxysugar epimerase involved in streptomycin biosynthesis, was identified as a highly acetylated protein by 2-DE-based proteomic analysis. The Lys70 residue, which is critical for the enzymatic activity of StrM, was the major acetylation site. Thus, acetylation of Lys70 was presumed to abolish enzymatic activity of StrM. In accordance with this notion, an S. griseus mutant producing the acetylation-mimic K70Q StrM hardly produced streptomycin, though the K70Q mutation apparently decreased the stability of StrM. A putative lysine acetyltransferase (KAT) SGR1683 in S. griseus, as well as the Escherichia coli KAT YfiQ, acetylated Lys70 of StrM in vitro. Furthermore, absolute quantification analysis estimated that 13% of StrM molecules were acetylated in mycelium grown in solid culture for 3days. These results indicate that StrM acetylation is of biological significance. We propose that StrM acetylation functions as a limiter of streptomycin biosynthesis in S. griseus.
  
  
  
  Protein acetylation has been extensively studied not only in eukaryotes, but also in prokaryotes. The acetylome has been analyzed in more than 14 bacterial species. Here, by comprehensive acetylome analysis, we showed that acetylation was found in proteins related to primary metabolism and translation in Streptomyces griseus, similarly to other bacteria. However, five proteins involved in secondary metabolism were also identified as acetylated proteins; these proteins are enzymes in the biosynthesis of streptomycin (StrB1 and StrS), grixazone (GriF), a nonribosomal peptide (NRPS1-2), and a siderophore (AlcC). Additionally, StrM in streptomycin biosynthesis was identified as a highly acetylated protein by 2-DE-based proteomic analysis; approximately 13% of StrM molecules were acetylated. The acetylation occurs at Lys70 to abolish the enzymatic activity of StrM, suggesting that StrM acetylation functions as a limiter of streptomycin biosynthesis in S. griseus. This is the first detailed analysis of protein acetylation of an enzyme involved in secondary metabolism.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ishigaki
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Genki
authors.initials: G
authors.lastname: Akanuma
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan; Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Sueharu
authors.initials: S
authors.lastname: Horinouchi
authors.affiliation: Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Biological Research Center, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: uskos@mail.ecc.u-tokyo.ac.jp.
authors.forename: Saori
authors.initials: S
authors.lastname: Kosono
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan. Electronic address: ayasuo@mail.ecc.u-tokyo.ac.jp.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohnishi
mesh_terms: D000107:Acetylation; D001426:Bacterial Proteins / Q000378:metabolism*; D013305:Streptomyces griseus / Q000378:metabolism*; D013307:Streptomycin / Q000096:biosynthesis*
chemical_list: D001426:Bacterial Proteins; D013307:Streptomycin
keywords: Acetylome; Lysine acetylation; Secondary metabolism; Streptomyces; Streptomycin