Crystal structure of Saccharomyces cerevisiae Aro8, a putative ?-aminoadipate aminotransferase.

ABSTRACT: ?-Aminoadipate aminotransferase (AAA-AT) catalyzes the amination of 2-oxoadipate to ?-aminoadipate in the fourth step of the ?-aminoadipate pathway of lysine biosynthesis in fungi. The aromatic aminotransferase Aro8 has recently been identified as an AAA-AT in Saccharomyces cerevisiae. This enzyme displays broad substrate selectivity, utilizing several amino acids and 2-oxo acids as substrates. Here we report the 1.91Å resolution crystal structure of Aro8 and compare it to AAA-AT LysN from Thermus thermophilus and human kynurenine aminotransferase II. Inspection of the active site of Aro8 reveals asymmetric cofactor binding with lysine-pyridoxal-5-phosphate bound within the active site of one subunit in the Aro8 homodimer and pyridoxamine phosphate and a HEPES molecule bound to the other subunit. The HEPES buffer molecule binds within the substrate-binding site of Aro8, yielding insights into the mechanism by which it recognizes multiple substrates and how this recognition differs from other AAA-AT/kynurenine aminotransferases.

SUBMITTER: Bulfer SL 

PROVIDER: S-EPMC3795499 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature