A Single Site Mutation Can Induce a Functional Promiscuity in Homoserine Kinase

L-Homoserine Kinase is crucial in the biosynthesis of Threonine, Isoleucine, and Methionine. Using computational tools herein, we provide new insight into the catalytic mechanism of L-homoserine kinase, showing a direct involvement of H139 as a catalytic base, in contrast to the previous consensus, where no involvement of a catalytic base was proposed. The proposed mechanism agrees with the finding that an H138L mutation reduces the Kinase activity but enhances a promiscuous function as ATPase activity