1aug
From Proteopedia
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CRYSTAL STRUCTURE OF THE PYROGLUTAMYL PEPTIDASE I FROM BACILLUS AMYLOLIQUEFACIENS
Overview
BACKGROUND: The N-terminal pyroglutamyl (pGlu) residue of peptide, hormones, such as thyrotropin-releasing hormone (TRH) and luteinizing, hormone releasing hormone (LH-RH), confers resistance to proteolysis by, conventional aminopeptidases. Specialized pyroglutamyl peptidases (PGPs), are able to cleave an N-terminal pyroglutamyl residue and thus control, hormonal signals. Until now, no direct or homology-based three-dimensional, structure was available for any PGP. RESULTS: The crystal structure of, pyroglutamyl peptidase I (PGP-I) from Bacillus amyloliquefaciens has been, determined to 1.6 A resolution. The crystallographic asymmetric unit of, PGP-I is a tetramer of four identical monomers related by, noncrystallographic 222 symmetry. The protein folds into an alpha/beta, globular domain with a hydrophobic core consisting of a twisted beta sheet, surrounded by five alpha helices. The structure allows the function of, most of the conserved residues in the PGP-I family to be identified. The, catalytic triad comprises Cys144, His168 and Glu81. CONCLUSIONS: The, catalytic site does not have a conventional oxyanion hole, although, Cys144, the sidechain of Arg91 and the dipole of an alpha helix could all, stabilize a negative charge. The catalytic site has an S1 pocket lined, with conserved hydrophobic residues to accommodate the pyroglutamyl, residue. Aside from the S1 pocket, there is no clearly defined mainchain, substrate-binding region, consistent with the lack of substrate, specificity. Although the overall structure of PGP-I resembles some other, alpha/beta twisted open-sheet structures, such as purine nucleoside, phosphorylase and cutinase, there are important differences in the, location and organization of the active-site residues. Thus, PGP-I belongs, to a new family of cysteine proteases.
About this Structure
1AUG is a Single protein structure of sequence from Bacillus amyloliquefaciens. Active as Pyroglutamyl-peptidase I, with EC number 3.4.19.3 Full crystallographic information is available from OCA.
Reference
The crystal structure of pyroglutamyl peptidase I from Bacillus amyloliquefaciens reveals a new structure for a cysteine protease., Odagaki Y, Hayashi A, Okada K, Hirotsu K, Kabashima T, Ito K, Yoshimoto T, Tsuru D, Sato M, Clardy J, Structure. 1999 Apr 15;7(4):399-411. PMID:10196127
Page seeded by OCA on Tue Nov 20 11:08:18 2007
