2cxi | pdb_00002cxi

Crystal Structure Of An N-terminal Fragment Of The Phenylalanyl-tRNA Synthetase Beta-Subunit From Pyrococcus Horikoshii

spinqualitylabelsall models 2cxi, resolution 1.94Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2cxi is a 3 chain structure with sequence from Pyrococcus horikoshii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: MSE Gene: PH0657 (Pyrococcus horikoshii) Activity: Phenylalanine--tRNA ligase, with EC number 6.1.1.20 Resources: FirstGlance, OCA, RCSB, PDBsum, TOPSAN Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed To achieve accurate aminoacylation of tRNAs with their cognate amino acids, errors in aminoacylation are corrected by the "editing" mechanism in several aminoacyl-tRNA synthetases. Phenylalanyl-tRNA synthetase (PheRS) hydrolyzes, or edits, misformed tyrosyl-tRNA with its editing domain in the beta subunit. We report the crystal structure of an N-terminal fragment of the PheRS beta subunit (PheRS-beta(N)) from the archaeon, Pyrococcus horikoshii, at 1.94-A resolution. PheRS-beta(N) includes the editing domain B3/4, which has archaea/eukarya-specific insertions/deletions and adopts a different orientation relative to other domains, as compared with that of bacterial PheRS. Surprisingly, most residues constituting the editing active-site pocket were substituted between the archaeal/eukaryal and bacterial PheRSs. We prepared Ala-substituted mutants of P. horikoshii PheRS for 16 editing-pocket residues, of which 12 are archaea/eukarya-specific and four are more widely conserved. On the basis of their activities, Tyr-adenosine was modeled on the B3/4-domain structure. First, the mutations of Leu-202, Ser-211, Asp-234, and Thr-236 made the PheRS incorrectly hydrolyze the cognate Phe-tRNA(Phe), indicating that these residues participate in the Tyr hydroxy group recognition and are responsible for discrimination against Phe. Second, the mutations of Leu-168 and Arg-223, which could interact with the tRNA 3'-terminal adenosine, reduced Tyr-tRNA(Phe) deacylation activity. Third, the mutations of archaea/eukarya-specific Gln-126, Glu-127, Arg-137, and Asn-217, which are proximal to the ester bond to be cleaved, also reduced Tyr-tRNA(Phe) deacylation activity. In particular, the replacement of Asn-217 abolished the activity, revealing its absolute requirement for the catalysis. Structural and mutational studies of the amino acid-editing domain from archaeal/eukaryal phenylalanyl-tRNA synthetase.,Sasaki HM, Sekine S, Sengoku T, Fukunaga R, Hattori M, Utsunomiya Y, Kuroishi C, Kuramitsu S, Shirouzu M, Yokoyama S Proc Natl Acad Sci U S A. 2006 Oct 3;103(40):14744-9. Epub 2006 Sep 26. PMID:17003130 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aminoacyl tRNA Synthetase

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