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Updated: Aug 23, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
alpha-Aminoadipate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus
Takashi Miyazaki1, Junichi Miyazaki1, Hisakazu Yamane1
1Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Abstract:
The extremely thermophilic bacterium Thermus thermophilus HB27 synthesizes lysine through alpha-aminoadipate (AAA). In this study, a T. thermophilus gene encoding the enzyme that catalyses transamination of AAA was cloned as a mammalian kynurenine/AAA aminotransferase (Kat2) gene homologue. A T. thermophilus mutant with disruption of the Kat2 homologue required a longer lag phase for growth and showed slower growth in minimal medium. Furthermore, addition of AAA or lysine shortened the lag phase and improved the growth rate. The Kat2 homologue was therefore termed lysN. LysN recognizes not only 2-oxoadipate, an intermediate of lysine biosynthesis, but also 2-oxoisocaproate, 2-oxoisovalerate and 2-oxo-3-methylvalerate, intermediates of leucine, valine and isoleucine biosyntheses, respectively, along with oxaloacetate, a compound in the TCA cycle, as an amino acceptor. These results suggest multiple roles of LysN in several cellular metabolic pathways including lysine and branched-chain amino acid biosyntheses.
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