1FCJ image
Entry Detail
PDB ID:
1FCJ
Keywords:
Title:
CRYSTAL STRUCTURE OF OASS COMPLEXED WITH CHLORIDE AND SULFATE
Biological Source:
Source Organism:
PDB Version:
Deposition Date:
2000-07-18
Release Date:
2000-10-18
Method Details:
Experimental Method:
Resolution:
2.00 Å
R-Value Free:
0.24
R-Value Work:
0.20
R-Value Observed:
0.20
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:O-ACETYLSERINE SULFHYDRYLASE
Chain IDs:A, B, C, D
Chain Length:322
Number of Molecules:4
Biological Source:Salmonella typhimurium
Primary Citation
Identification of an allosteric anion-binding site on O-acetylserine sulfhydrylase: structure of the enzyme with chloride bound.
J.Mol.Biol. 303 279 286 (2000)
PMID: 11023792 DOI: 10.1006/jmbi.2000.4109

Abstact

A new crystal structure of O-acetylserine sulfhydrylase (OASS) has been solved with chloride bound at an allosteric site and sulfate bound at the active site. The bound anions result in a new "inhibited" conformation, that differs from the "open" native or "closed" external aldimine conformations. The allosteric site is located at the OASS dimer interface. The new inhibited structure involves a change in the position of the "moveable domain" (residues 87-131) to a location that differs from that in the open or closed forms. Formation of the external aldimine with substrate is stabilized by interaction of the alpha-carboxyl group of the substrate with a substrate-binding loop that is part of the moveable domain. The inhibited conformation prevents the substrate-binding loop from interacting with the alpha-carboxyl group, and hinders formation of the external Schiff base and thus subsequent chemistry. Chloride may be an analog of sulfide, the physiological inhibitor. Finally, these results suggest that OASS represents a new class of PLP-dependent enzymes that is regulated by small anions.

Legend

Protein

Chemical

Disease

Primary Citation of related structures