1sjw

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spinqualitylabelsall models 1sjw, resolution 1.35Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure of polyketide cyclase SnoaL

Overview

SnoaL belongs to a family of small polyketide cyclases, which catalyse, ring closure steps in the biosynthesis of polyketide antibiotics produced, in Streptomyces. Several of these antibiotics are among the most used, anti-cancer drugs currently in use. The crystal structure of SnoaL, involved in nogalamycin biosynthesis, with a bound product, has been, determined to 1.35 A resolution. The fold of the subunit can be described, as a distorted alpha+beta barrel, and the ligand is bound in the, hydrophobic interior of the barrel. The 3D structure and site-directed, mutagenesis experiments reveal that the mechanism of the intramolecular, aldol condensation catalysed by SnoaL is different from that of the, classical aldolases, which employ covalent Schiff base formation or a, metal ion cofactor. The invariant residue Asp121 acts as an acid/base, catalyst during the reaction. Stabilisation of the enol(ate) intermediate, is mainly achieved by the delocalisation of the electron pair over the, extended pi system of the substrate. These polyketide cyclases thus form, of family of enzymes with a unique catalytic strategy for aldol, condensation.

About this Structure

1SJW is a Single protein structure of sequence from Streptomyces nogalater with NGV as ligand. Full crystallographic information is available from OCA.

Reference

Structure of the polyketide cyclase SnoaL reveals a novel mechanism for enzymatic aldol condensation., Sultana A, Kallio P, Jansson A, Wang JS, Niemi J, Mantsala P, Schneider G, EMBO J. 2004 May 5;23(9):1911-21. Epub 2004 Apr 8. PMID:15071504

Page seeded by OCA on Sun Nov 25 00:39:39 2007