title: The N-terminal fragment of Acanthamoeba polyphaga mimivirus tyrosyl-tRNA synthetase (TyrRS(apm)) is a monomer in solution.
abstract: Acanthamoeba polyphaga mimivirus tyrosyl-tRNA synthetase (TyrRSapm) was the first reported aminoacyl-tRNA synthetase of viral origin. The previous crystal structure of TyrRSapm showed a non-canonical orientation of the dimer conformation and the CP1 domain, responsible for dimer formation, displays a major modification of a motif structurally conserved in other TyrRS structures. An earlier study reported that Bacillus stearothermophilus N-terminal TyrRS exists as a dimer under native conditions. N-terminal TyrRSapm (ΔTyrRSapm, 1-234 aa) was constructed to remove the C-terminal anticodon-binding domain. Here we show by Ferguson plot analysis and analytical ultracentrifugation that ΔTyrRSapm exists as a monomer and contains a disulfide-bridge. The ΔTyrRSapm loses the ability to bind tRNA(Tyr), however it remains active in pyrophosphate exchange with similar ligand dissociation constants as the full-length enzyme.
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: Aparajita
authors: A
authors: Choudhury
authors: Rajat
authors: R
authors: Banerjee
mesh_terms: D020816:Amino Acid Motifs; D002942:Circular Dichroism; D011756:Diphosphates / Q000737:chemistry* / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry; D006801:Humans; D007700:Kinetics; D008024:Ligands; D056686:Mimiviridae / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics; D009154:Mutation; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012996:Solutions; D013816:Thermodynamics; D014448:Tyrosine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014461:Ultracentrifugation; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D011756:Diphosphates; D004220:Disulfides; D008024:Ligands; D011994:Recombinant Proteins; D012996:Solutions; D014764:Viral Proteins; C107241:diphosphoric acid; D014448:Tyrosine-tRNA Ligase