title: Substrate specificity of mammalian N-terminal α-amino methyltransferase NRMT.
abstract: N-Terminal methylation of free α-amino groups is a post-translational modification of proteins that was first described 30 years ago but has been studied very little. In this modification, the initiating M residue is cleaved and the exposed α-amino group is mono-, di-, or trimethylated by NRMT, a recently identified N-terminal methyltransferase. Currently, all known eukaryotic α-amino-methylated proteins have a unique N-terminal motif, M-X-P-K, where X is A, P, or S. NRMT can also methylate artificial substrates in vitro in which X is G, F, Y, C, M, K, R, N, Q, or H. Methylation efficiencies of N-terminal amino acids are variable with respect to the identity of X. Here we use in vitro peptide methylation assays and substrate immunoprecipitations to show that the canonical M-X-P-K methylation motif is not the only one recognized by NRMT. We predict that N-terminal methylation is a widespread post-translational modification and that there is interplay between N-terminal acetylation and N-terminal methylation. We also use isothermal calorimetry experiments to demonstrate that NRMT can efficiently recognize and bind to its fully methylated products.
authors: Department of Microbiology, Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors: Janusz J
authors: JJ
authors: Petkowski
authors: Christine E
authors: CE
authors: Schaner Tooley
authors: Lissa C
authors: LC
authors: Anderson
authors: Igor A
authors: IA
authors: Shumilin
authors: Jeremy L
authors: JL
authors: Balsbaugh
authors: Jeffrey
authors: J
authors: Shabanowitz
authors: Donald F
authors: DF
authors: Hunt
authors: Wladek
authors: W
authors: Minor
authors: Ian G
authors: IG
authors: Macara
mesh_terms: D006801:Humans; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D011499:Protein Processing, Post-Translational / Q000235:genetics; D013379:Substrate Specificity / Q000235:genetics
chemical_list: D010446:Peptide Fragments; D008780:Methyltransferases; C551913:NTMT1 protein, human