TAILIEUCHUNG - Báo cáo khoa học: Kinetic and mechanistic characterization of Mycobacterium tuberculosis glutamyl–tRNA synthetase and determination of its oligomeric structure in solution

Antigen binding to the B-cell receptor (BCR) of pre-mature B lymphocytes induces their apoptotic cell death, but binding to the BCR of mature B lymphocytes triggers activation and proliferation. Binding to pre-mature B lymphocytes is thought not only to function as a mechanism to exclude B-cell clones that possess the ability to react with self-antigen, but also to act as a defense mechanism in auto-immune diseases. | Kinetic and mechanistic characterization of Mycobacterium tuberculosis glutamyl-tRNA synthetase and determination of its oligomeric structure in solution Stefano Paravisi1 Gianluca Fumagalli1 Milena Riva1 Paola Morandi1 Rachele Morosi1 Peter V. Konarev2 3 Maxim V. Petoukhov2 3 Stephane Bernier4 Robert Chenevert4 Dmitri I. Svergun2 3 Bruno Curti1 and Maria A. Vanoni1 1 Dipartimento di Scienze Biomolecolari e Biotecnologie University degli Studi di Milano Italy 2 European Molecular Biology Laboratory Hamburg Germany 3 Institute of Crystallography Russian Academy of Sciences Moscow Russia 4 Department de Chimie CREFSIP Universite Laval Canada Keywords glutamyl-tRNA reductase glutamyl-tRNA synthetase Mycobacterium tuberculosis protein synthesis tetrapyrrole synthesis Correspondence M. A. Vanoni Dipartimento di Scienze Biomolecolari e Biotecnologie Universita degli Studi di Milano Via Celoria 26 20131 Milan Italy Fax 39 025 031 4895 Tel 39 025 031 4901 E-mail Received 15 October 2008 revised 23 December 2008 accepted 24 December 2008 doi Mycobacterium tuberculosis glutamyl-tRNA synthetase Mt-GluRS encoded by Rv2992c was overproduced in Escherichia coli cells and purified to homogeneity. It was found to be similar to the other well-characterized GluRS especially the E. coli enzyme with respect to the requirement for bound tRNAGlu to produce the glutamyl-AMP intermediate and the steady-state kinetic parameters kcat 130 min-1 and KM for tRNA IM and ATP 78 IM but to differ by a one order of magnitude higher KM value for L-Glu mM . At variance with the E. coli enzyme among the several compounds tested as inhibitors only pyrophosphate and the glutamyl-AMP analog glutamol-AMP were effective with Ki values in the IM range. The observed inhibition patterns are consistent with a random binding of ATP and L-Glu to the enzyme-tRNA complex. Mt-GluRS which is predicted by genome analysis to be of the non-discriminating .

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