title: Stoichiometry of Saccharomyces cerevisiae lysine methylation: insights into non-histone protein lysine methyltransferase activity.
abstract: Post-translational lysine methylation is well established as a regulator of histone activity; however, it is emerging that these modifications are also likely to play extensive roles outside of the histone code. Here we obtain new insights into non-histone lysine methylation and protein lysine methyltransferase (PKMT) activity by elucidating absolute stoichiometries of lysine methylation, using mass spectrometry and absolute quantification (AQUA), in wild-type and 5 PKMT gene deletion strains of Saccharomyces cerevisiae. By analyzing 8 sites of methylation in 3 non-histone proteins, elongation factor 1-α (EF1α), elongation factor 2 (EF2), and 60S ribosomal protein L42-A/B (Rpl42ab), we find that production of preferred methylation states on individual lysine residues is commonplace and likely occurs through processive PKMT activity, Class I PKMTs can be associated with processive methylation, lysine residues are selectively methylated by specific PKMTs, and lysine methylation exists over a broad range of stoichiometries. Together these findings suggest that specific sites and forms of lysine methylation may play specialized roles in the regulation of non-histone protein activity. We also uncover new relationships between two proteins previously characterized as PKMTs, SEE1 and EFM1, in EF1α methylation and show that past characterizations of EFM1 as having direct PKMT activity may require reinterpretation.
authors: NSW Systems Biology Initiative, University of New South Wales , Sydney, New South Wales 2052, Australia.
authors: Gene
authors: G
authors: Hart-Smith
authors: Samantha Z
authors: SZ
authors: Chia
authors: Jason K K
authors: JK
authors: Low
authors: Matthew J
authors: MJ
authors: McKay
authors: Mark P
authors: MP
authors: Molloy
authors: Marc R
authors: MR
authors: Wilkins
mesh_terms: D000595:Amino Acid Sequence; D008239:Lysine / Q000737:chemistry* / Q000378:metabolism; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000737:chemistry / Q000378:metabolism; D020652:Peptide Elongation Factor 2 / Q000737:chemistry / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D020648:Peptide Elongation Factor 1; D020652:Peptide Elongation Factor 2; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D008780:Methyltransferases; D008239:Lysine