Crystal structure of enoyl-coenzyme A (CoA) hydratase at 2.5 angstroms resolution: a spiral fold defines the CoA-binding pocket.
The crystal structure of rat liver mitochondrial enoyl-coenzyme A (CoA) hydratase complexed with the potent inhibitor acetoacetyl-CoA has been refined at 2.5 angstroms resolution. This enzyme catalyses the reversible addition of water to alpha,beta-unsaturated enoyl-CoA thioesters, with nearly diffusion-controlled reaction rates for the best substrates. Enoyl-CoA hydratase is a hexamer of six identical subunits of 161 kDa molecular mass for the complex. The hexamer is a dimer of trimers. The monomer is folded into a right-handed spiral of four turns, followed by two small domains which are involved in trimerization. Each turn of the spiral consists of two beta-strands and an alpha-helix. The mechanism for the hydratase/dehydratase reaction follows a syn-stereochemistry, a preference that is opposite to the nonenzymatic reaction. The active-site architecture agrees with this stereochemistry. It confirms the importance of Glu164 as the catalytic acid for providing the alpha-proton during the hydratase reaction. It also shows the importance of Glu144 as the catalytic base for the activation of a water molecule in the hydratase reaction. The comparison of an unliganded and a liganded active site within the same crystal form shows a water molecule in the unliganded subunit. This water molecule is bound between the two catalytic glutamates and could serve as the activated water during catalysis.
Engel
C K
CK
European Molecular Biology Laboratory, Heidelberg, Germany.
Mathieu
M
M
Zeelen
J P
JP
Hiltunen
J K
JK
Wierenga
R K
RK
D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004746:Enoyl-CoA Hydratase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D004791:Enzyme Inhibitors; D018698:Glutamic Acid / Q000378:metabolism; D008930:Mitochondria, Liver / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D051381:Rats
D000214:Acyl Coenzyme A; D004791:Enzyme Inhibitors; C010667:acetoacetyl CoA; D018698:Glutamic Acid; D004746:Enoyl-CoA Hydratase