Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Seryl-tRNA synthetase (SerRS) is a class II aminoacyl-tRNA synthetase that catalyzes serine activation and its transfer to cognate tRNA Ser . Previ-ous biochemical and structural studies have revealed that bacterial- and methanogenic-type SerRSs employ different strategies of substrate recogni-tion. | ỊFEBS Journal Structural flexibility of the methanogenic-type seryl-tRNA synthetase active site and its implication for specific substrate recognition Silvija Bilokapic1 Jasmina Rokov Plavec1 Nenad Ban2 and Ivana Weygand-Durasevic1 1 Department of Chemistry Faculty of Science University of Zagreb Croatia 2 Department of Biology Institute of Molecular Biology and Biophysics Swiss FederalInstitute of Technology Zurich Switzerland Keywords conformationalflexibility motif 2 loop seryl-tRNA synthetase specificity of substrate recognition synthetase tRNA model Correspondence I. Weygand-Durasevic Department of Chemistry Faculty of Science University of Zagreb Horvatovac 102a 10000 Zagreb Croatia Fax 385 1 460 6401 Tel 385 1 460 6230 E-mail weygand@chem.pmf.hr Received 20 February 2008 revised 21 March 2008 accepted 26 March 2008 doi 10.1111 j.1742-4658.2008.06423.x Seryl-tRNA synthetase SerRS is a class II aminoacyl-tRNA synthetase that catalyzes serine activation and its transfer to cognate tRNASer. Previous biochemical and structural studies have revealed that bacterial- and methanogenic-type SerRSs employ different strategies of substrate recognition. In addition to other idiosyncratic features such as the active site zinc ion and the unique fold of the N-terminal tRNA-binding domain methanogenic-type SerRS is in comparison with bacterial homologues characterized by a notable shortening of the motif 2 loop. Mutational analysis of Methanosarcina barkeri SerRS mMbSerRS was undertaken to identify the active site residues that ensure the specificity of amino acid and tRNA 3 -end recognition. Residues predicted to contribute to the amino acid specificity were selected for mutation according to the crystal structure of mMbSerRS complexed with its cognate aminoacyl-adenylate whereas those involved in binding of the tRNA 3 -end were identified and mutagenized on the basis of modeling the mMbSerRS tRNA complex. Although mMbSerRSs variants with an altered serine-binding pocket .