1cm5
From Proteopedia
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CRYSTAL STRUCTURE OF C418A,C419A MUTANT OF PFL FROM E.COLI
Overview
Pyruvate formate-lyase (PFL) from Escherichia coli uses a radical, mechanism to reversibly cleave the C1-C2 bond of pyruvate using the Gly, 734 radical and two cysteine residues (Cys 418, Cys 419). We have, determined by X-ray crystallography the structures of PFL (non-radical, form), its complex with the substrate analog oxamate, and the C418A,C419A, double mutant. The atomic model (a dimer of 759-residue monomers), comprises a 10-stranded beta/alpha barrel assembled in an antiparallel, manner from two parallel five-stranded beta-sheets; this architecture, resembles that of ribonucleotide reductases. Gly 734 and Cys 419, positioned at the tips of opposing hairpin loops, meet in the apolar, barrel center (Calpha-Sgamma = 3.7 A). Oxamate fits into a compact pocket, where C2 is juxtaposed with Cys 418Sgamma (3.3 A), which in turn is close, to Cys 419Sgamma (3.7 A). Our model of the active site is suggestive of a, snapshot of the catalytic cycle, when the pyruvate-carbonyl awaits attack, by the Cys 418 thiyl radical. We propose a homolytic radical mechanism for, PFL that involves Cys 418 and Cys 419 both as thiyl radicals, with, distinct chemical functions.
About this Structure
1CM5 is a Single protein structure of sequence from Escherichia coli with CO3 and NA as ligands. Active as Formate C-acetyltransferase, with EC number 2.3.1.54 Full crystallographic information is available from OCA.
Reference
Structure and mechanism of the glycyl radical enzyme pyruvate formate-lyase., Becker A, Fritz-Wolf K, Kabsch W, Knappe J, Schultz S, Volker Wagner AF, Nat Struct Biol. 1999 Oct;6(10):969-75. PMID:10504733
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