title: Co- and post-translational modifications of the 26S proteasome in yeast.
abstract: The yeast (Saccharomyces cerevisiae) 26S proteasome consists of the 19S regulatory particle (19S RP) and 20S proteasome subunits. We detected comprehensively co- and post-translational modifications of these subunits using proteomic techniques. First, using MS/MS, we investigated the N-terminal modifications of three 19S RP subunits, Rpt1, Rpn13, and Rpn15, which had been unclear, and found that the N-terminus of Rpt1 is not modified, whereas that of Rpn13 and Rpn15 is acetylated. Second, we identified a total of 33 Ser/Thr phosphorylation sites in 15 subunits of the proteasome. The data obtained by us and other groups reveal that the 26S proteasome contains at least 88 phospho-amino acids including 63 pSer, 23 pThr, and 2 pTyr residues. Dephosphorylation treatment of the 19S RP with lambda phosphatase resulted in a 30% decrease in ATPase activity, demonstrating that phosphorylation is involved in the regulation of ATPase activity in the proteasome. Third, we tried to detect glycosylated subunits of the 26S proteasome. However, we identified neither N- and O-linked oligosaccharides nor O-linked beta-N-acetylglucosamine in the 19S RP and 20S proteasome subunits. To date, a total of 110 co- and post-translational modifications, including N(alpha)-acetylation, N(alpha)-myristoylation, and phosphorylation, in the yeast 26S proteasome have been identified.
authors.affiliation: Graduate School of Nanobioscience, Yokohama City University, Yokohama, Japan.
authors.forename: Julia
authors.initials: J
authors.lastname: Kikuchi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iwafune
authors.forename: Tomoko
authors.initials: T
authors.lastname: Akiyama
authors.forename: Akiko
authors.initials: A
authors.lastname: Okayama
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Noriaki
authors.initials: N
authors.lastname: Arakawa
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Kimura
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hirano
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D006031:Glycosylation; D008969:Molecular Sequence Data; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease