Manipulating unconventional CH-based hydrogen bonding in a methyltransferase via noncanonical amino acid mutagenesis.

Published

Journal Article

Recent studies have demonstrated that the active sites of S-adenosylmethionine (AdoMet)-dependent methyltransferases form strong carbon-oxygen (CH···O) hydrogen bonds with the substrate's sulfonium group that are important in AdoMet binding and catalysis. To probe these interactions, we substituted the noncanonical amino acid p-aminophenylalanine (pAF) for the active site tyrosine in the lysine methyltransferase SET7/9, which forms multiple CH···O hydrogen bonds to AdoMet and is invariant in SET domain enzymes. Using quantum chemistry calculations to predict the mutation's effects, coupled with biochemical and structural studies, we observed that pAF forms a strong CH···N hydrogen bond to AdoMet that is offset by an energetically unfavorable amine group rotamer within the SET7/9 active site that hinders AdoMet binding and activity. Together, these results illustrate that the invariant tyrosine in SET domain methyltransferases functions as an essential hydrogen bonding hub and cannot be readily substituted by residues bearing other hydrogen bond acceptors.

Full Text

Duke Authors

Cited Authors

  • Horowitz, S; Adhikari, U; Dirk, LMA; Del Rizzo, PA; Mehl, RA; Houtz, RL; Al-Hashimi, HM; Scheiner, S; Trievel, RC

Published Date

  • August 15, 2014

Published In

Volume / Issue

  • 9 / 8

Start / End Page

  • 1692 - 1697

PubMed ID

  • 24914947

Pubmed Central ID

  • 24914947

Electronic International Standard Serial Number (EISSN)

  • 1554-8937

Digital Object Identifier (DOI)

  • 10.1021/cb5001185

Language

  • eng

Conference Location

  • United States