Repository of the Academy's Library

STRUCTURE AND CATALYSIS OF ACYLAMINOACYL PEPTIDASE: CLOSED AND OPEN SUBUNITS OF A DIMER OLIGOPEPTIDASE

Harmat, Veronika and Domokos, Klarissza and Karancsiné Menyhárd, Dóra and Palló, Anna and Szeltner, Zoltán and Szamosi, Ilona and Beke-Somfai, Tamás and Náray-Szabó, Gábor and Polgár, László (2011) STRUCTURE AND CATALYSIS OF ACYLAMINOACYL PEPTIDASE: CLOSED AND OPEN SUBUNITS OF A DIMER OLIGOPEPTIDASE. J. Biol. Chem., 286 (3). pp. 1987-1998. ISSN 0021-9258 (print) 1083-351X (online)

[img] PDF
JBiolChemHarmat.pdf
Restricted to Registered users only

Download (2018Kb) | Request a copy

Abstract

Acylaminoacyl peptidase from Aeropyrum pernix is a homodimer that belongs to the prolyl oligopeptidase family. The monomer subunit is composed of one hydrolase and one propeller domain. Previous crystal structure determinations revealed that the propeller domain obstructed the access of substrate to the active site of both subunits. Here we investigated the structure and the kinetics of two mutant enzymes in which the aspartic acid of the catalytic triad was changed to alanine or asparagine. Using different substrates, we have determined the pH dependence of specificity rate constants, the rate-limiting step of catalysis, the binding of substrates and inhibitors. The catalysis considerably depended both on the kind of mutation and on the nature of the substrate. The results were interpreted in terms of alterations in the position of the catalytic histidine side chain as demonstrated with crystal structure determination of the native and the two mutant structures (D524N, D524A). Unexpectedly, in the homodimeric structures, only one subunit displayed the closed form of the enzyme. The other subunit exhibited an open gate to the catalytic site, thus revealing the structural basis that controls the oligopeptidase activity. The open form of the native enzyme displayed the catalytic triad in distorted, inactive state. The mutations affected the closed, active form of the enzyme, disrupting its catalytic triad. It is concluded that the two forms are at equilibrium, and the substrates bind by the conformational selection mechanism.

Item Type: Article
Subjects: Q Science / természettudomány > QD Chemistry / kémia
Depositing User: Prof Gábor Náray-Szabó
Date Deposited: 10 Jul 2011 04:51
Last Modified: 02 Oct 2012 06:02
URI: http://real.mtak.hu/id/eprint/2731

Actions (login required)

View Item View Item