1fcj

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spinqualitylabelsall models 1fcj, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF OASS COMPLEXED WITH CHLORIDE AND SULFATE

Overview

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.

About this Structure

1FCJ is a Single protein structure of sequence from Salmonella typhimurium with SO4, CL and PLP as ligands. Active as Cysteine synthase, with EC number 2.5.1.47 Full crystallographic information is available from OCA.

Reference

Identification of an allosteric anion-binding site on O-acetylserine sulfhydrylase: structure of the enzyme with chloride bound., Burkhard P, Tai CH, Jansonius JN, Cook PF, J Mol Biol. 2000 Oct 20;303(2):279-86. PMID:11023792

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