2r82

From Proteopedia

Revision as of 13:24, 4 May 2008

Template:STRUCTURE 2r82

Pyruvate phosphate dikinase (PPDK) triple mutant R219E/E271R/S262D adapts a second conformational state

Overview

Crystals of pyruvate phosphate dikinase in complex with a substrate analogue inhibitor, phosphonopyruvate (K(i) = 3 microM), have been obtained in the presence of Mg(2+). The structure has been determined and refined at 2.2 A resolution, revealing that the Mg(2+)-bound phosphonopyruvate binds in the alpha/beta-barrel's central channel, at the C-termini of the beta-strands. The mode of binding resembles closely the previously proposed PEP substrate binding mode, inferred by the homology of the structure (but not sequence homology) to pyruvate kinase. Kinetic analysis of site-directed mutants, probing residues involved in inhibitor binding, showed that all mutations resulted in inactivation, confirming the key role that these residues play in catalysis. Comparison between the structure of the PPDK-phosphonopyruvate complex and the structures of two complexes of pyruvate kinase, one with Mg(2+)-bound phospholactate and the other with Mg(2+)-oxalate and ATP, revealed that the two enzymes share some key features that facilitate common modes of substrate binding. There are also important structural differences; most notably, the machinery for acid/base catalysis is different.

About this Structure

2R82 is a Single protein structure of sequence from Clostridium symbiosum. Full crystallographic information is available from OCA.

Reference

Pyruvate site of pyruvate phosphate dikinase: crystal structure of the enzyme-phosphonopyruvate complex, and mutant analysis., Herzberg O, Chen CC, Liu S, Tempczyk A, Howard A, Wei M, Ye D, Dunaway-Mariano D, Biochemistry. 2002 Jan 22;41(3):780-7. PMID:11790099 Page seeded by OCA on Sun May 4 16:24:12 2008