title: The Saccharomyces cerevisiae poly(A)-binding protein is subject to multiple post-translational modifications, including the methylation of glutamic acid.
abstract: Poly(A)-binding protein in mouse and man was recently found to be highly post-translationally modified. Here we analysed an ortholog of this protein, Pab1 from Saccharomyces cerevisiae, to assess the conservation and thus likely importance of these modifications. Pab1 showed the presence of six sites of methylated glutamate, five sites of lysine acetylation, and one phosphorylation of serine. Many modifications on Pab1 showed either complete conservation with those on human or mouse PABPC1, were present on nearby residues and/or were present in the same domain(s). The conservation of methylated glutamate, an unusual modification, was of particular note and suggests a conserved function. Comparison of methylated glutamate sites in human, mouse and yeast poly(A)-binding protein, along with methylation sites catalysed by CheR L-glutamyl protein methyltransferase from Salmonella typhimurium, revealed that the methylation of glutamate preferentially occurs in EE and DE motifs or other small regions of acidic amino acids. The conservation of methylated glutamate in the same protein between mouse, man and yeast suggests the presence of a eukaryotic l-glutamyl protein methyltransferase and that the modification is of functional significance.
authors: Systems Biology Laboratory, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Jason K K
authors: JK
authors: Low
authors: Systems Biology Laboratory, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Gene
authors: G
authors: Hart-Smith
authors: Systems Biology Laboratory, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
authors: Melissa A
authors: MA
authors: Erce
authors: Systems Biology Laboratory, School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: marc.wilkins@unsw.edu.au.
authors: Marc R
authors: MR
authors: Wilkins
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D018698:Glutamic Acid / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D039102:Poly(A)-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D039102:Poly(A)-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C450100:pab1 protein, S cerevisiae; D018698:Glutamic Acid
keywords: Glutamate methylation; Methylation; Methyltransferase; Poly(A) binding protein; Post-translational modification; Saccharomyces cerevisiae