X-ray structure of MalY from Escherichia coli: a pyridoxal 5'-phosphate-dependent enzyme acting as a modulator in mal gene expression.

ABSTRACT: MalY represents a bifunctional pyridoxal 5'-phosphate-dependent enzyme acting as a beta-cystathionase and as a repressor of the maltose regulon. Here we present the crystal structures of wild-type and A221V mutant protein. Each subunit of the MalY dimer is composed of a large pyridoxal 5'-phosphate-binding domain and a small domain similar to aminotransferases. The structural alignment with related enzymes identifies residues that are generally responsible for beta-lyase activity and depicts a unique binding mode of the pyridoxal 5'-phosphate correlated with a larger, more flexible substrate-binding pocket. In a screen for MalY mutants with reduced mal repressor properties, mutations occurred in three clusters: I, 83-84; II, 181-189 and III, 215-221, which constitute a clearly distinguishe

SUBMITTER: Clausen T 

PROVIDER: S-EPMC305623 | biostudies-literature | 2000 Mar

REPOSITORIES: biostudies-literature