Domain-domain communication in a miniature archaebacterial tRNA synthetase.
The three-dimensional structure of tRNA is organized into two domains-the acceptor-TPsiC minihelix with the amino acid attachment site and a second, anticodon-containing, stem-loop domain. Aminoacyl-tRNA synthetases have a structural organization that roughly recapitulates the two-domain organization of tRNAs-an older primary domain that contains the catalytic center and interacts with the minihelix and a secondary, more recent, domain that makes contacts with the anticodon-containing arm. The latter contacts typically are essential for enhancement of the catalytic constant k(cat) through domain-domain communication. Methanococcus jannaschii tyrosyl-tRNA synthetase is a miniature synthetase with a tiny secondary domain suggestive of an early synthetase evolving from a one-domain to a two-domain structure. Here we demonstrate functional interactions with the anticodon-containing arm of tRNA that involve the miniaturized secondary domain. These interactions appear not to include direct contacts with the anticodon triplet but nonetheless lead to domain-domain communication. Thus, interdomain communication may have been established early in the evolution from one-domain to two-domain structures.
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The Skaggs Institute for Chemical Biology, The Scripps Research Institute, Beckman Center, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Schimmel
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D000215:Acylation; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D019641:DNA, Archaeal; D006801:Humans; D007700:Kinetics; D017017:Methanococcus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012365:RNA, Transfer, Tyr / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014448:Tyrosine-tRNA Ligase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D019641:DNA, Archaeal; D012365:RNA, Transfer, Tyr; D014448:Tyrosine-tRNA Ligase