Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1074/jbc.M115.645689
Title (Primary) Structural basis of the stereospecificity of bacterial B12-dependent 2-hydroxyisobutyryl-CoA mutase
Author Kurteva-Yaneva, N.; Zahn, M.; Weichler, M.-T.; Starke, R.; Harms, H.; Müller, R.H.; Sträter, N.; Rohwerder, T.
Source Titel Journal of Biological Chemistry
Year 2015
Department UMB; PROTEOM
Volume 290
Page From 9727
Page To 9737
Language englisch
Keywords adenosylcobalamin (AdoCbl); crystal structure; stereoselectivity; substrate specificity; X-ray crystallography; (S)-3-hydroxybutyryl-CoA; 2-hydroxyisobutyryl-CoA; acyl-CoA mutase; pivalyl-CoA
UFZ wide themes RU4
Abstract Bacterial coenzyme B12-dependent 2-hydroxyisobutyryl-CoA mutase (HCM) is a radical enzyme catalyzing the stereospecific interconversion of (S)-3-hydroxybutyryl- and 2-hydroxyisobutyryl-CoA. It consists of two subunits, HcmA and HcmB. To characterize the determinants of substrate specificity, we have analyzed the crystal structure of HCM from Aquincola tertiaricarbonis in complex with coenzyme B12 and the substrates (S)-3-hydroxybutyryl- and 2-hydroxyisobutyryl-CoA in alternative binding. Compared to the well-studied structure of bacterial and mitochondrial B12-dependent methylmalonyl-CoA mutase (MCM), HCM has a highly conserved domain architecture. However, inspection of the substrate binding site identified amino acid residues not present in MCM, namely HcmA IleA90 and AspA117. AspA117 determines the orientation of the hydroxyl group of the acyl-CoA esters by H-bond formation, thus determining stereospecificity of catalysis. Accordingly, HcmA D117A and D117V mutations resulted in significantly increased activity towards (R)-hydroxybutyryl-CoA. Besides interconversion of hydroxylated acyl-CoA esters, wild-type HCM as well as HcmA I90V and I90A mutant enzymes could also isomerize pivalyl- and isovaleryl-CoA, albeit at >10 times lower rates than the favorite substrate (S)-3-hydroxybutyryl-CoA. The nonconservative mutation HcmA D117V, however, resulted in an enzyme showing high activity towards pivalyl-CoA. Structural requirements for binding and isomerization of highly branched acyl-CoA substrates such as 2-hydroxyisobutyryl- and pivalyl-CoA, possessing tertiary and quaternary carbon atoms, respectively, are discussed.
Persistent UFZ Identifier
Kurteva-Yaneva, N., Zahn, M., Weichler, M.-T., Starke, R., Harms, H., Müller, R.H., Sträter, N., Rohwerder, T. (2015):
Structural basis of the stereospecificity of bacterial B12-dependent 2-hydroxyisobutyryl-CoA mutase
J. Biol. Chem. 290 , 9727 - 9737 10.1074/jbc.M115.645689