Crystal structure of a putative aspartate aminotransferase belonging to subgroup IV.
Protein TT0402 from Thermus thermophilus HB8 exhibits about 30-35% sequence identity with proteins belonging to subgroup IV in the aminotransferase family of the fold-type I pyridoxal 5'-phosphate (PLP)-dependent enzymes. In this study, we determined the crystal structure of TT0402 at 2.3 A resolution (R(factor) = 19.9%, R(free) = 23.6%). The overall structure of TT0402 exhibits the fold conserved in aminotransferases, and is most similar to that of the Escherichia coli phosphoserine aminotransferase, which belongs to subgroup IV but shares as little as 13% sequence identity with TT0402. Kinetic assays confirmed that TT0402 has higher transamination activities with the amino group donor, L-glutamate, and somewhat lower activities with L-aspartate. These results indicate that TT0402 is a subgroup IV aminotransferase for the synthesis/degradation of either L-aspartate or a similar compound.
Katsura
Yasuhiro
Y
RIKEN Genomic Sciences Center, Tsurumi, Yokohama, Japan.
Shirouzu
Mikako
M
Yamaguchi
Hiroto
H
Ishitani
Ryuichiro
R
Nureki
Osamu
O
Kuramitsu
Seiki
S
Hayashi
Hideyuki
H
Yokoyama
Shigeyuki
S
D000595:Amino Acid Sequence; D001219:Aspartate Aminotransferases / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000145:classification / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D040681:Structural Homology, Protein; D013379:Substrate Specificity; D016963:Thermus thermophilus / Q000201:enzymology*
D001426:Bacterial Proteins; D001219:Aspartate Aminotransferases