HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 5, 3210-3219, January 31, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/5/3210    most recent M210431200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wang, Y. Articles by Guo, H.-C. Search for Related Content PubMed PubMed Citation Articles by Wang, Y. Articles by Guo, H.-C. Social Bookmarking                      What's this?

Two-step Dimerization for Autoproteolysis to Activate Glycosylasparaginase^*

Yeming Wang and Hwai-Chen Guo

From the Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118-2526

Glycosylasparaginase (GA) is an amidase and belongs to a novel family of N-terminal nucleophile hydrolases that use a similar autoproteolytic processing mechanism to generate a mature/active enzyme from a single chain protein precursor. From bacteria to eukaryotes, GAs are conserved in primary sequences, tertiary structures, and activation of amidase activity by intramolecular autoproteolysis. An evolutionarily conserved His-Asp-Thr sequence is cleaved to generate a newly exposed N-terminal threonine, which plays a central role in both autoproteolysis and in its amidase activity. We have recently determined the crystal structure of the bacterial GA precursor at 1.9-Å resolution, which reveals a highly distorted and energetically unfavorable conformation at the scissile peptide bond. A mechanism of autoproteolysis via an N-O acyl shift was proposed to relieve these conformational strains. However, it is not understood how the polypeptide chain distortion was generated and preserved during the folding of GA to trigger autoproteolysis. An obstacle to our understanding of GA autoproteolysis is the uncertainty concerning its quaternary structure in solution. Here we have revisited this question and show that GA forms dimers in solution. Mutants with alterations at the dimer interface cannot form dimers and are impaired in the autoproteolytic activation. This suggests that dimerization of GA plays an essential role in autoproteolysis to activate the amidase activity. Comparison of the melting temperatures of GA dimers before and after autoproteolysis suggests two states of dimerization in the process of enzyme maturation. A two-step dimerization mechanism to trigger autoproteolysis is proposed to accommodate the data presented here as well as those in the literature.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				J. Q. Davies, G.-W. Chang, S. Yona, S. Gordon, M. Stacey, and H.-H. Lin The Role of Receptor Oligomerization in Modulating the Expression and Function of Leukocyte Adhesion-G Protein-coupled Receptors J. Biol. Chem., September 14, 2007; 282(37): 27343 - 27353. [Abstract] [Full Text] [PDF]

				H.-H. Lin, G.-W. Chang, J. Q. Davies, M. Stacey, J. Harris, and S. Gordon Autocatalytic Cleavage of the EMR2 Receptor Occurs at a Conserved G Protein-coupled Receptor Proteolytic Site Motif J. Biol. Chem., July 23, 2004; 279(30): 31823 - 31832. [Abstract] [Full Text] [PDF]