Controlling electron transfer in Acyl-CoA oxidases and dehydrogenases: a structural view.
Plants produce a unique peroxisomal short chain-specific acyl-CoA oxidase (ACX4) for beta-oxidation of lipids. The short chain-specific oxidase has little resemblance to other peroxisomal acyl-CoA oxidases but has an approximately 30% sequence identity to mitochondrial acyl-CoA dehydrogenases. Two biochemical features have been linked to structural properties by comparing the structures of short chain-specific Arabidopsis thaliana ACX4 with and without a substrate analogue bound in the active site to known acyl-CoA oxidases and dehydrogenase structures: (i) a solvent-accessible acyl binding pocket is not required for oxygen reactivity, and (ii) the oligomeric state plays a role in substrate pocket architecture but is not linked to oxygen reactivity. The structures indicate that the acyl-CoA oxidases may encapsulate the electrons for transfer to molecular oxygen by blocking the dehydrogenase substrate interaction site with structural extensions. A small binding pocket observed adjoining the flavin adenine dinucleotide N5 and C4a atoms could increase the number of productive encounters between flavin adenine dinucleotide and O2.
Mackenzie
Jenny
J
Biostructure Group, Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark.
Pedersen
Lise
L
Arent
Susan
S
Henriksen
Anette
A
D042964:Acyl-CoA Dehydrogenase / Q000737:chemistry*; D042962:Acyl-CoA Oxidase / Q000737:chemistry*; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D004583:Electrons; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D055672:Static Electricity; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D010940:Plant Proteins; C495585:ACX4 protein, Arabidopsis; D042962:Acyl-CoA Oxidase; D042964:Acyl-CoA Dehydrogenase; D010100:Oxygen