title: Critical role of zinc ion on E. coli glutamyl-queuosine-tRNA(Asp) synthetase (Glu-Q-RS) structure and function.
abstract: Glutamyl-queuosine-tRNA(Asp) synthetase (Glu-Q-RS) and glutamyl-tRNA synthetase (GluRS), differ widely by their function although they share close structural resemblance within their catalytic core of GluRS. In particular both Escherichia coli GluRS and Glu-Q-RS contain a single zinc-binding site in their putative tRNA acceptor stem-binding domain. It has been shown that the zinc is crucial for correct positioning of the tRNA(Glu) acceptor-end in the active site of E. coli GluRS. To address the role of zinc ion in Glu-Q-RS, the C101S/C103S Glu-Q-RS variant is constructed. Energy dispersive X-ray fluorescence show that the zinc ion still remained coordinated but the variant became structurally labile and acquired aggregation capacity. The extent of aggregation of the protein is significantly decreased in presence of the small substrates and more particularly by adenosine triphosphate. Addition of zinc increased significantly the solubility of the variant. The aminoacylation assay reveals a decrease in activity of the variant even after addition of zinc as compared to the wild-type, although the secondary structure of the protein is not altered as shown by the Fourier transform infrared spectroscopy study.
authors: Department of Biotechnology and Dr. BC Guha Centre for Genetic Engineering and Biotechnology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, India.
authors: Sutapa
authors: S
authors: Ray
authors: Victor
authors: V
authors: Banerjee
authors: Mickael
authors: M
authors: Blaise
authors: Baisakhi
authors: B
authors: Banerjee
authors: Kali Pada
authors: KP
authors: Das
authors: Daniel
authors: D
authors: Kern
authors: Rajat
authors: R
authors: Banerjee
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D005975:Glutamate-tRNA Ligase / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C487511:YadB protein, E coli; D000604:Amino Acyl-tRNA Synthetases; D005975:Glutamate-tRNA Ligase; D015032:Zinc