2b76

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spinqualitylabelsall models 2b76, resolution 3.300Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

E. coli Quinol fumarate reductase FrdA E49Q mutation

Overview

The Escherichia coli complex II homologues succinate:ubiquinone, oxidoreductase (SQR, SdhCDAB) and menaquinol:fumarate oxidoreductase (QFR, FrdABCD) have remarkable structural homology at their dicarboxylate, binding sites. Although both SQR and QFR can catalyze the interconversion, of fumarate and succinate, QFR is a much better fumarate reductase, and, SQR is a better succinate oxidase. An exception to the conservation of, amino acids near the dicarboxylate binding sites of the two enzymes is, that there is a Glu (FrdA Glu-49) near the covalently bound FAD cofactor, in most QFRs, which is replaced with a Gln (SdhA Gln-50) in SQRs. The role, of the amino acid side chain in enzymes with Glu/Gln/Ala substitutions at, FrdA Glu-49 and SdhA Gln-50 has been investigated in this study. The data, demonstrate that the mutant enzymes with Ala substitutions in either QFR, or SQR remain functionally similar to their wild type counterparts. There, were, however, dramatic changes in the catalytic properties when Glu and, Gln were exchanged for each other in QFR and SQR. The data show that QFR, and SQR enzymes are more efficient succinate oxidases when Gln is in the, target position and a better fumarate reductase when Glu is present., Overall, structural and catalytic analyses of the FrdA E49Q and SdhA Q50E, mutants suggest that coulombic effects and the electronic state of the FAD, are critical in dictating the preferred directionality of the, succinate/fumarate interconversions catalyzed by the complex II, superfamily.

About this Structure

2B76 is a Protein complex structure of sequences from Escherichia coli with FLC, FES, F3S, SF4, FAD and MQ7 as ligands. Active as Succinate dehydrogenase, with EC number 1.3.99.1 Full crystallographic information is available from OCA.

Reference

Fumarate reductase and succinate oxidase activity of Escherichia coli complex II homologs are perturbed differently by mutation of the flavin binding domain., Maklashina E, Iverson TM, Sher Y, Kotlyar V, Andrell J, Mirza O, Hudson JM, Armstrong FA, Rothery RA, Weiner JH, Cecchini G, J Biol Chem. 2006 Apr 21;281(16):11357-65. Epub 2006 Feb 15. PMID:16484232

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