Stabilization of non-productive conformations underpins rapid electron transfer to electron-transferring flavoprotein.
Crystal structures of protein complexes with electron-transferring flavoprotein (ETF) have revealed a dual protein-protein interface with one region serving as anchor while the ETF FAD domain samples available space within the complex. We show that mutation of the conserved Glu-165beta in human ETF leads to drastically modulated rates of interprotein electron transfer with both medium chain acyl-CoA dehydrogenase and dimethylglycine dehydrogenase. The crystal structure of free E165betaA ETF is essentially identical to that of wild-type ETF, but the crystal structure of the E165betaA ETF.medium chain acyl-CoA dehydrogenase complex reveals clear electron density for the FAD domain in a position optimal for fast interprotein electron transfer. Based on our observations, we present a dynamic multistate model for conformational sampling that for the wild-type ETF. medium chain acyl-CoA dehydrogenase complex involves random motion between three distinct positions for the ETF FAD domain. ETF Glu-165beta plays a key role in stabilizing positions incompatible with fast interprotein electron transfer, thus ensuring high rates of complex dissociation.
Department of Biochemistry, University of Leicester, Henry Wellcome Building, Lancaster Road, LE1 7RH, Leicester United Kingdom.
Helen S
HS
Toogood
Adam
A
van Thiel
Nigel S
NS
Scrutton
David
D
Leys
D042964:Acyl-CoA Dehydrogenase / Q000378:metabolism; D018360:Crystallography, X-Ray; D050893:Dimethylglycine Dehydrogenase; D004579:Electron Transport; D044927:Electron-Transferring Flavoproteins / Q000737:chemistry*; D004583:Electrons; D005420:Flavoproteins / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D024101:Mitochondrial Proteins; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010089:Oxidoreductases, N-Demethylating / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
D044927:Electron-Transferring Flavoproteins; D005420:Flavoproteins; D024101:Mitochondrial Proteins; D042964:Acyl-CoA Dehydrogenase; D010089:Oxidoreductases, N-Demethylating; C494398:DMGDH protein, human; D050893:Dimethylglycine Dehydrogenase