Crystal Structure of an Aldo-keto Reductase MGG_00097 from Magnaporthe grisea.

Abstract

The enzyme MGG_00097 from rice blast fungus (Magnaporthe grisea) is a NADPH-dependent oxidoreductase, involved in synthesizing glycerol from dihydroxyacetone phosphate and dihydroxyacetone. The 35.5-kDa monomer belongs to the aldo-keto reductase superfamily, characterized by a highly conserved catalytic tetrad. This study, elucidates the expression, purification, and kinetic properties of recombinant MGG_00097. The ternary complex of MGG_00097 with NADP+ and glycerol was refined to a 2.9 Å resolution, revealing critical insights into substrate binding and catalysis. NADP+ binds within the active site, with residues Ser221, Leu223, Ser225, Lys271, Ser272, Ser273, Thr274, Arg277, and Asn281 forming the substrate and cofactor-binding pockets. A Y56A mutation reveals the open conformation of the cofactor-binding pocket, with Glu29 and Gln226 functioning as hinge residues for the conformational changes upon cofactor binding. These findings contribute to the understanding of MGG_00097's catalytic mechanism and offer a basis for further biochemical and potential biotechnological applications.