Conserved residue His-257 of Vibrio cholerae flavin transferase ApbE plays a critical role in substrate binding and catalysis.

ABSTRACT: The flavin transferase ApbE plays essential roles in bacterial physiology, covalently incorporating FMN cofactors into numerous respiratory enzymes that use the integrated cofactors as electron carriers. In this work we performed a detailed kinetic and structural characterization of Vibrio cholerae WT ApbE and mutants of the conserved residue His-257, to understand its role in substrate binding and in the catalytic mechanism of this family. Bi-substrate kinetic experiments revealed that ApbE follows a random Bi Bi sequential kinetic mechanism, in which a ternary complex is formed, indicating that both substrates must be bound to the enzyme for the reaction to proceed. Steady-state kinetic analyses show that the turnover rates of His-257 mutants are significantly smaller than those o

SUBMITTER: Fang X 

PROVIDER: S-EPMC6746461 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature