Structural insights into the mechanism of intramolecular proteolysis

Abstract

A variety of proteins, including glycosylasparaginase, have recently been found to activate functions by self-catalyzed peptide bond rearrangements from single-chain precursors. Here we present the 1.9 Δ crystal structures of glycosylasparaginase precursors that are able to autoproteolyze via an N → O acyl shift. Several conserved residues are aligned around the scissile peptide bond that is in a highly strained trans peptide bond configuration. The structure illustrates how a nucleophilic side chain may attack the scissile peptide bond at the immediate upstream backbone carbonyl and provides an understanding of the structural basis for peptide bond cleavage via an N → O or N → S acyl shift that is used by various groups of intramolecular autoprocessing proteins.