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.
Toogood
Helen S
HS
Department of Biochemistry, University of Leicester, Henry Wellcome Building, Lancaster Road, LE1 7RH, Leicester United Kingdom.
van Thiel
Adam
A
Scrutton
Nigel S
NS
Leys
David
D
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