Open AccessA third crystal form of Wolinella succinogenes quinol:fumarate reductase reveals domain closure at the site of fumarate reduction
Author(s) -
Lancaster C. Roy D.,
Groß Roland,
Simon Jörg
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2001.02053.x
Subject(s) - fumarate reductase , chemistry , reductase , flavoprotein , crystal structure , binding site , enzyme , active site , stereochemistry , thermus thermophilus , crystallography , biochemistry , succinate dehydrogenase , escherichia coli , gene
Quinol:fumarate reductase (QFR) is a membrane protein complex that couples the reduction of fumarate to succinate to the oxidation of quinol to quinone. Previously, the crystal structure of QFR from Wolinella succinogenes was determined based on two different crystal forms, and the site of fumarate binding in the flavoprotein subunit A of the enzyme was located between the FAD‐binding domain and the capping domain [Lancaster, C.R.D., Kröger, A., Auer, M., & Michel, H. (1999) Nature 402 , 377–385]. Here we describe the structure of W. succinogenes QFR based on a third crystal form and refined at 3.1 Å resolution. Compared with the previous crystal forms, the capping domain is rotated in this structure by approximately 14° relative to the FAD‐binding domain. As a consequence, the topology of the dicarboxylate binding site is much more similar to those of membrane‐bound and soluble fumarate reductase enzymes from other organisms than to that found in the previous crystal forms of W. succinogenes QFR. This and the effects of the replacement of Arg A301 by Glu or Lys by site‐directed mutagenesis strongly support a common mechanism for fumarate reduction in this superfamily of enzymes.