The power of two: arginine 51 and arginine 239* from a neighboring subunit are essential for catalysis in α-amino-β-carboxymuconate-epsilon-semialdehyde decarboxylase.

ABSTRACT: Although the crystal structure of α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase from Pseudomonas fluorescens was solved as a dimer, this enzyme is a mixture of monomer, dimer, and higher order structures in solution. In this work, we found that the dimeric state, not the monomeric state, is the functionally active form. Two conserved arginine residues are present in the active site: Arg-51 and an intruding Arg-239* from the neighboring subunit. In this study, they were each mutated to alanine and lysine, and all four mutants were catalytically inactive. The mutants were also incapable of accommodating pyridine-2,6-dicarboxylic acid, a competitive inhibitor of the native enzyme, suggesting that the two Arg residues are involved in substrate binding. It was also observed that the de

SUBMITTER: Huo L 

PROVIDER: S-EPMC3829401 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature