Towards elucidation of hydrolytic proofreading mechanism by mutational analysis of isoleucyl-tRNA synthetase synthetic site

Franičević, Nina (2011) Towards elucidation of hydrolytic proofreading mechanism by mutational analysis of isoleucyl-tRNA synthetase synthetic site. Diploma thesis, Faculty of Science > Department of Biology.

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Abstract

Aminoacyl-tRNA synthetases (aaRSs) catalyze covalent attachment of amino acids to their cognate tRNAs. Due to inherent inability of some aaRS to recognize cognate amino acid with a high accuracy, these aaRS have developed hydrolytic editing mechanisms to correct mistakes made during aminoacylation. Pre-transfer editing clears the noncognate aminoacyl-adenylates, while misacylated tRNAs are corrected by the post-transfer editing. Recent data show that pre-transfer editing by isoleucyl-tRNA synthetase (IleRS) occurs within the synthetic site, where noncognate aminoacyl-adenylate is kinetically partitioned between hydrolysis and the transfer step. Site-directed mutagenesis and kinetic characterization of the obtained IleRS synthetic site mutants contributed to understanding of the mechanisms of amino acid activation and noncognate aminoacyl-adenylate hydrolysis. Thus, pre-transfer editing depends on precise conformation of the synthetic site that positions the noncognate aminoacyl-adenylate in the hydrolytic subsite. We propose that Gly56, Tyr59 and Glu561 have important role in discrimination of the cognate and noncognate substrates and in positioning of the catalytic water molecule.

Item Type: Thesis (Diploma thesis)
Keywords: aminoacyl-tRNA synthetases, editing mechanisms, pre-transfer editing, site-directed mutagenesis, isoleucyl-tRNA synthetase, hydrolysis of aminoacyl-adenylates
Supervisor: Gruić Sovulj, Ita
Date: 2011
Number of Pages: 91
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Grozdana Sirotic
Date Deposited: 21 Jul 2014 10:28
Last Modified: 16 Feb 2016 13:57
URI: http://digre.pmf.unizg.hr/id/eprint/2528

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