The 2.9 Å Crystal Structure of T. thermophilus Seryl-tRNA Synthetase Complexed with tRNA$^{Ser}

• Published in: Science (American Association for the Advancement of Science) Vol. 263; no. 5152; pp. 1404 - 1410
• Main Authors: Biou, Valérie, Yaremchuk, Anna, Tukalo, Michael, Cusack, Stephen
• Format: Journal Article
• Language: English
• Published: United States American Society for the Advancement of Science 11.03.1994
• Subjects: Active sites; Adenosine Triphosphate - metabolism; Amino Acid Sequence; Anticodon; Base Composition; Base Sequence; Binding Sites; Crystal structure; Crystallography, X-Ray; Crystals; Electron density; Models, Molecular; Molecular Sequence Data; Molecules; Monomers; Nucleic Acid Conformation; Nucleotides; Protein Conformation; Protein Structure, Secondary; RNA, Transfer, Amino Acyl - chemistry; RNA, Transfer, Amino Acyl - metabolism; Serine-tRNA Ligase - chemistry; Serine-tRNA Ligase - metabolism; Substrate Specificity; Thermus thermophilus - enzymology; Transfer RNA; Yeasts
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.8128220

The crystal structure of Thermus thermophilus seryl-transfer RNA synthetase, a class 2 aminoacyl-tRNA synthetase, complexed with a single tRNA$^{Ser}$ molecule was solved at 2.9 Å resolution. The structure revealed how insertion of conserved base G20b from the D loop into the core of the tRNA determines the orientation of the long variable arm, which is a characteristic feature of most serine specific tRNAs. On tRNA binding, the antiparallel coiled-coil domain of one subunit of the synthetase makes contacts with the variable arm and TΨC loop of the tRNA and directs the acceptor stem of the tRNA into the active site of the other subunit. Specificity depends principally on recognition of the shape of tRNA$^{Ser}$ through backbone contacts and secondarily on sequence specific interactions.