title: Purification, crystallisation and preliminary crystallographic studies of succinate:ubiquinone oxidoreductase from Escherichia coli.
abstract: A membrane protein complex, succinate dehydrogenase (SQR) from Escherichia coli has been purified and crystallised. This enzyme is composed of four subunits containing FAD, three iron-sulphur clusters and one haem b as prosthetic groups. The obtained crystals belong to the hexagonal space group P6(3) with the unit-cell dimensions of a=b=123.8 A and c=214.6 A. An asymmetric unit of the crystals contains one SQR monomer (M(r) 120 kDa). A data set is now available at 4.0 A resolution with 88.1% completeness and 0.106 R(merge). We have obtained a molecular replacement solution that shows sensible molecular packing, using the soluble domain of E. coli QFR (fumarate reductase) as a search model. The packing suggests that E. coli SQR is a crystallographic trimer rather than a dimer as observed for the E. coli QFR.
authors.affiliation: Department of Biochemistry, Uppsala University, Sweden.
authors.forename: Susanna
authors.initials: S
authors.lastname: Törnroth
authors.forename: Victoria
authors.initials: V
authors.lastname: Yankovskaya
authors.forename: Gary
authors.initials: G
authors.lastname: Cecchini
authors.forename: So
authors.initials: S
authors.lastname: Iwata
mesh_terms: D003461:Crystallography; D042963:Electron Transport Complex II; D004926:Escherichia coli / Q000201:enzymology*; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D005650:Fumarates / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D007425:Intracellular Membranes / Q000201:enzymology; D007506:Iron-Sulfur Proteins / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification*; D010088:Oxidoreductases / Q000737:chemistry / Q000302:isolation & purification*; D011808:Quinone Reductases / Q000737:chemistry / Q000302:isolation & purification; D013385:Succinate Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification*; D019802:Succinic Acid / Q000737:chemistry / Q000378:metabolism
chemical_list: D005650:Fumarates; D007506:Iron-Sulfur Proteins; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D005182:Flavin-Adenine Dinucleotide; D006418:Heme; C032005:fumaric acid; D019802:Succinic Acid; D010088:Oxidoreductases; D042963:Electron Transport Complex II; C424907:quinol fumarate reductase; D013385:Succinate Dehydrogenase; D011808:Quinone Reductases; C073412:sulfide quinone reductase