Cofactor specificity motifs and the induced fit mechanism in class I ketol-acid reductoisomerases.

ABSTRACT: Although most sequenced members of the industrially important ketol-acid reductoisomerase (KARI) family are class I enzymes, structural studies to date have focused primarily on the class II KARIs, which arose through domain duplication. In the present study, we present five new crystal structures of class I KARIs. These include the first structure of a KARI with a six-residue β2αB (cofactor specificity determining) loop and an NADPH phosphate-binding geometry distinct from that of the seven- and 12-residue loops. We also present the first structures of naturally occurring KARIs that utilize NADH as cofactor. These results show insertions in the specificity loops that confounded previous attempts to classify them according to loop length. Lastly, we explore the conformational changes that

SUBMITTER: Cahn JK 

PROVIDER: S-EPMC4550535 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature