Peptide backbone conformation affects the substrate preference of protein arginine methyltransferase I.
Asymmetric dimethylation of arginine side chains is a common post-translational modification of eukaryotic proteins, which serves mostly to regulate protein-protein interactions. The modification is catalyzed by type I protein arginine methyltransferases, PRMT1 being the predominant member of the family. Determinants of substrate specificity of these enzymes are poorly understood. The Nuclear poly(A) binding protein 1 (PABPN1) is methylated by PRMT1 at 13 arginine residues located in RXR sequences in the protein's C-terminal domain. We have identified a preferred site for PRMT1-catalyzed methylation in PABPN1 and in a corresponding synthetic peptide. Variants of these substrates were analyzed by steady-state kinetic analysis and mass spectrometry. The data indicate that initial methylation is directed toward the preferred arginine residue by an N-terminally adjacent proline. Enhanced methylation upon peptide cyclization suggests that induction of a reverse turn structure is the basis for the ability of the respective proline residue to enable preferred methylation of the neighboring arginine residue, and this notion is supported by far-UV circular dichroism spectroscopy. We suggest that the formation of a reverse turn facilitates the access of arginine side chains to the active sites of PRMT1, which are located in the central cavity of a doughnut-shaped PRMT1 homodimer.
Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Germany.
Knut
K
Kölbel
Christian
C
Ihling
Uwe
U
Kühn
Ines
I
Neundorf
Silke
S
Otto
Jan
J
Stichel
Dina
D
Robaa
Annette G
AG
Beck-Sickinger
Andrea
A
Sinz
Elmar
E
Wahle
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis; D006801:Humans; D008745:Methylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry*; D039103:Poly(A)-Binding Protein II / Q000737:chemistry / Q000235:genetics; D011392:Proline; D011484:Protein-Arginine N-Methyltransferases / Q000737:chemistry* / Q000378:metabolism*; D051381:Rats; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity
D010446:Peptide Fragments; D010455:Peptides; D039103:Poly(A)-Binding Protein II; D012097:Repressor Proteins; D011392:Proline; C099988:PRMT1 protein, human; C541817:PRMT1 protein, rat; D011484:Protein-Arginine N-Methyltransferases