A newly uncovered group of distantly related lysine methyltransferases preferentially interact with molecular chaperones to regulate their activity

• Published in: PLoS genetics Vol. 9; no. 1; p. e1003210
• Main Authors: Cloutier, Philippe, Lavallée-Adam, Mathieu, Faubert, Denis, Blanchette, Mathieu, Coulombe, Benoit
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01-01-2013; Public Library of Science (PLoS)
• Subjects: Amino Acid Sequence; Amino acids; Amyotrophic Lateral Sclerosis - genetics; Amyotrophic Lateral Sclerosis - metabolism; Biology; Chemistry; Epigenetics; Experiments; Frontotemporal Dementia - genetics; Frontotemporal Dementia - metabolism; Gene expression; Genetic aspects; Genome, Human; Health aspects; HEK293 Cells; HSP70 Heat-Shock Proteins - metabolism; HSP90 Heat-Shock Proteins - metabolism; Humans; Lysine; Mass Spectrometry; Medical research; Medicine; Methylation; Methyltransferases; Methyltransferases - classification; Methyltransferases - genetics; Methyltransferases - isolation & purification; Methyltransferases - metabolism; Molecular chaperones; Molecular Chaperones - genetics; Molecular Chaperones - metabolism; Molecular Sequence Data; Mutation; Myositis, Inclusion Body - genetics; Myositis, Inclusion Body - metabolism; Neuromuscular diseases; Osteitis Deformans - genetics; Osteitis Deformans - metabolism; Peptides; Phylogenetics; Phylogeny; Physiological aspects; Protein Processing, Post-Translational; Proteins; Canada
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1003210

Methylation is a post-translational modification that can affect numerous features of proteins, notably cellular localization, turnover, activity, and molecular interactions. Recent genome-wide analyses have considerably extended the list of human genes encoding putative methyltransferases. Studies on protein methyltransferases have revealed that the regulatory function of methylation is not limited to epigenetics, with many non-histone substrates now being discovered. We present here our findings on a novel family of distantly related putative methyltransferases. Affinity purification coupled to mass spectrometry shows a marked preference for these proteins to associate with various chaperones. Based on the spectral data, we were able to identify methylation sites in substrates, notably trimethylation of K135 of KIN/Kin17, K561 of HSPA8/Hsc70 as well as corresponding lysine residues in other Hsp70 isoforms, and K315 of VCP/p97. All modification sites were subsequently confirmed in vitro. In the case of VCP, methylation by METTL21D was stimulated by the addition of the UBX cofactor ASPSCR1, which we show directly interacts with the methyltransferase. This stimulatory effect was lost when we used VCP mutants (R155H, R159G, and R191Q) known to cause Inclusion Body Myopathy with Paget's disease of bone and Fronto-temporal Dementia (IBMPFD) and/or familial Amyotrophic Lateral Sclerosis (ALS). Lysine 315 falls in proximity to the Walker B motif of VCP's first ATPase/D1 domain. Our results indicate that methylation of this site negatively impacts its ATPase activity. Overall, this report uncovers a new role for protein methylation as a regulatory pathway for molecular chaperones and defines a novel regulatory mechanism for the chaperone VCP, whose deregulation is causative of degenerative neuromuscular diseases.