alpha-Aminoadipate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus.
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.
Miyazaki
Takashi
T
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Miyazaki
Junichi
J
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Yamane
Hisakazu
H
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Nishiyama
Makoto
M
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
D051307:2-Aminoadipate Transaminase; D015074:2-Aminoadipic Acid / Q000378:metabolism; D003001:Cloning, Molecular; D003470:Culture Media; D006358:Hot Temperature; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D016963:Thermus thermophilus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*
D003470:Culture Media; D011994:Recombinant Proteins; D015074:2-Aminoadipic Acid; D000637:Transaminases; D051307:2-Aminoadipate Transaminase