Mechanism of phosphoryl transfer catalyzed by shikimate kinase from Mycobacterium tuberculosis

Abstract

The structural mechanism of the catalytic functioning of shikimate kinase from Mycobacterium tuberculosis was investigated on the basis of a series of high-resolution crystal structures corresponding to individual steps in the enzymatic reaction. The catalytic turnover of shikimate and ATP into the products shikimate-3-phosphate and ADP, followed by release of ADP, was studied in the crystalline environment. Based on a comparison of the structural states before initiation of the reaction and immediately after the catalytic step, we derived a structural model of the transition state that suggests that phosphoryl transfer proceeds with inversion by an in-line associative mechanism. The random sequential binding of shikimate and nucleotides is associated with domain movements. We identified a synergic mechanism by which binding of the first substrate may enhance the affinity for the second substrate.