1yni

From Proteopedia

---

Revision as of 04:48, 21 November 2007

proteopedia linkproteopedia link

spinqualitylabelsall models 1yni, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of N-Succinylarginine Dihydrolase, AstB, bound to Substrate and Product, an Enzyme from the Arginine Catabolic Pathway of Escherichia coli

Overview

The ammonia-producing arginine succinyltransferase pathway is the major, pathway in Escherichia coli and related bacteria for arginine catabolism, as a sole nitrogen source. This pathway consists of five steps, each, catalyzed by a distinct enzyme. Here we report the crystal structure of, N-succinylarginine dihydrolase AstB, the second enzyme of the arginine, succinyltransferase pathway, providing the first structural insight into, enzymes from this pathway. The enzyme exhibits a pseudo 5-fold symmetric, alpha/beta propeller fold of circularly arranged betabetaalphabeta modules, enclosing the active site. The crystal structure indicates clearly that, this enzyme belongs to the amidinotransferase (AT) superfamily and that, the active site contains a Cys-His-Glu triad characteristic of the AT, superfamily. Structures of the complexes of AstB with the reaction product, and a C365S mutant with bound the N-succinylarginine substrate suggest a, catalytic mechanism that consists of two cycles of hydrolysis and ammonia, release, with each cycle utilizing a mechanism similar to that proposed, for arginine deiminases. Like other members of the AT superfamily of, enzymes, AstB possesses a flexible loop that is disordered in the absence, of substrate and assumes an ordered conformation upon substrate binding, shielding the ligand from the bulk solvent, thereby controlling substrate, access and product release.

About this Structure

1YNI is a Single protein structure of sequence from Escherichia coli with K and SUG as ligands. Full crystallographic information is available from OCA.

Reference

Crystal structure of N-succinylarginine dihydrolase AstB, bound to substrate and product, an enzyme from the arginine catabolic pathway of Escherichia coli., Tocilj A, Schrag JD, Li Y, Schneider BL, Reitzer L, Matte A, Cygler M, J Biol Chem. 2005 Apr 22;280(16):15800-8. Epub 2005 Feb 9. PMID:15703173

Page seeded by OCA on Wed Nov 21 06:55:55 2007