Peptide Backbone Conformation Affects the Substrate Preference of Protein Arginine Methyltransferase I
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- 作者：Knut K枚lbel ; Christian Ihling ; Uwe K眉hn ; Ines Neundorf ; Silke Otto ; Jan Stichel ; Dina Robaa ; Annette G. Beck-Sickinger ; Andrea Sinz ; Elmar Wahle
- 刊名：Biochemistry
- 出版年：2012
- 出版时间：July 10, 2012
- 年：2012
- 卷：51
- 期：27
- 页码：5463-5475
- 全文大小：518K
- 年卷期：v.51,no.27(July 10, 2012)
- ISSN：1520-4995
文摘
Asymmetric dimethylation of arginine side chains is a common post-translational modification of eukaryotic proteins, which serves mostly to regulate protein鈥損rotein 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鈥檚 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.