Structure of an N-terminally truncated selenophosphate synthetase from Aquifex aeolicus.
Selenophosphate synthetase (SPS) catalyzes the activation of selenide with ATP to synthesize selenophosphate, the reactive selenium donor for biosyntheses of both the 21st amino acid selenocysteine and 2-selenouridine nucleotides in tRNA anticodons. The crystal structure of an N-terminally (25 residues) truncated fragment of SPS (SPS-DeltaN) from Aquifex aeolicus has been determined at 2.0 A resolution. The structure revealed SPS to be a two-domain alpha/beta protein, with domain folds that are homologous to those of PurM-superfamily proteins. In the crystal, six monomers of SPS-DeltaN form a hexamer of 204 kDa, whereas the molecular weight estimated by ultracentrifugation was approximately 63 kDa, which is comparable to the calculated weight of the dimer (68 kDa).
Systems and Structural Biology Center, RIKEN Yokohama Institute, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
Eiko
E
Matsumoto
Shun Ichi
SI
Sekine
Ryogo
R
Akasaka
Yumi
Y
Otta
Kazushige
K
Katsura
Mio
M
Inoue
Tatsuya
T
Kaminishi
Takaho
T
Terada
Mikako
M
Shirouzu
Shigeyuki
S
Yokoyama
D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000201:enzymology*; D002384:Catalysis; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010710:Phosphates / Q000138:chemical synthesis; D010770:Phosphotransferases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D018036:Selenium Compounds / Q000138:chemical synthesis; D017279:Selenocysteine / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014461:Ultracentrifugation
D010710:Phosphates; D018036:Selenium Compounds; D017279:Selenocysteine; C076818:selenophosphate; D010770:Phosphotransferases; C062762:selenophosphate synthetase