2UZJ image
Entry Detail
PDB ID:
2UZJ
Keywords:
Title:
Crystal structure of the mature streptococcal cysteine protease, mSpeB
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2008-09-16
Release Date:
2009-09-08
Method Details:
Experimental Method:
Resolution:
1.55 Å
R-Value Free:
0.22
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:STREPTOPAIN
Chain IDs:A, B
Chain Length:253
Number of Molecules:2
Biological Source:STREPTOCOCCUS PYOGENES
Ligand Molecules
Primary Citation
Structure of the Mature Streptococcal Cysteine Protease Exotoxin Mspeb in its Active Dimeric Form.
J.Mol.Biol. 393 693 ? (2009)
PMID: 19712682 DOI: 10.1016/J.JMB.2009.08.046

Abstact

Invasive infections of Streptococcus pyogenes are dependent on the cysteine protease streptococcal pyrogenic exotoxin B. Previous structures of the enzyme have not disclosed the proper active-site configuration. Here, the crystal structure of the mature enzyme is presented to 1.55 A, disclosing a homodimer. A serine from one subunit inserts into the active site of the other to donate to the oxyanion hole and coordinates the ligand proximal to the active-site cysteine. Dimerization is unique to the mature form and is clearly a prerequisite for catalysis. The present structure supports a tripartite switch system that is triggered upon dimerization and substrate binding: (1) liberation of the active-site histidine from an inactive configuration, (2) relocation of residues blocking the substrate binding pockets and (3) repositioning of two active-site tryptophans to settle in the active configuration. Based on the present structure, the active site of clan CA cysteine proteases is expanded and a detailed mechanism of the deacylation mechanism is proposed. The results may have applications for the development of protease inhibitors specific to bacterial cysteine proteases.

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Primary Citation of related structures