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

Authors

  • Stacie L. Bulfer,

    1. Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan
    Current affiliation:
    1. Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA
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  • Joseph S. Brunzelle,

    1. Northwestern Synchrotron Research Center, Life Sciences Collaborative Access Team, Northwestern University Center for Synchrotron Research, Argonne, Illinois
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  • Raymond C. Trievel

    Corresponding author
    • Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan
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Correspondence to: Raymond Trievel, Department of Biological Chemistry, University of Michigan, 5301 Medical Science Research Building III, 1150 West Medical Center Drive, SPC 5606, Ann Arbor, MI 48109. E-mail: rtrievel@umich.edu

Abstract

α-Aminoadipate aminotransferase (AAA-AT) catalyzes the amination of 2-oxoadipate to α-aminoadipate in the fourth step of the α-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.

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