1bs0

From Proteopedia

Revision as of 12:22, 18 December 2007

PLP-DEPENDENT ACYL-COA SYNTHASE

Overview

8-Amino-7-oxononanoate synthase (or 8-amino-7-ketopelargonate synthase; EC, 2.3.1.47; AONS) catalyses the decarboxylative condensation of l-alanine, and pimeloyl-CoA in the first committed step of biotin biosynthesis. We, have cloned, over-expressed and purified AONS from Escherichia coli and, determined the crystal structures of the apo and PLP-bound forms of the, enzyme. The protein is a symmetrical homodimer with a tertiary structure, and active site organisation similar to, but distinct from, those of other, PLP-dependent enzymes whose three-dimensional structures are known. The, critical PLP-binding lysine of AONS is located at the end of a deep cleft, that allows access of the pantothenate arm of pimeloyl-CoA. A cluster of, positively charged residues at the entrance to this cleft forms a putative, diphosphate binding site for CoA. The structure of E. coli AONS enables, identification of the key residues of the PLP-binding site and thus, provides a framework with which to understand the biochemical mechanism, which is similar to that catalysed by 5-aminolevulinate synthase and two, other alpha-oxoamine synthases. Although AONS has a low overall sequence, similarity with the catalytic domains of other alpha-oxoamine synthases, the structure reveals the regions of significant identity to be, functionally important. This suggests that the organisation of the, conserved catalytic residues in the active site is similar for all enzymes, of this sub-class of PLP-dependent enzymes and they share a common, mechanism. Knowledge of the three-dimensional structure of AONS will, enable characterisation of the structural features of this enzyme, sub-family that are responsible for this important type of reaction.

About this Structure

1BS0 is a Single protein structure of sequence from Escherichia coli with SO4 as ligand. Active as 8-amino-7-oxononanoate synthase, with EC number 2.3.1.47 Known structural/functional Site: . Full crystallographic information is available from OCA.

Reference

The crystal structure of 8-amino-7-oxononanoate synthase: a bacterial PLP-dependent, acyl-CoA-condensing enzyme., Alexeev D, Alexeeva M, Baxter RL, Campopiano DJ, Webster SP, Sawyer L, J Mol Biol. 1998 Nov 27;284(2):401-19. PMID:9813126

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