title: Groups on the side chain of T252 in Escherichia coli leucyl-tRNA synthetase are important for discrimination of amino acids and cell viability.
abstract: Leucyl-tRNA synthetase (LeuRS) catalyzes the leucylation of tRNA(Leu). To maintain the fidelity of protein biosynthesis, LeuRS also catalyzes the editing reaction. In the present work, highly conserved T252 in the T-rich region within CP1 domain of Escherichia coli LeuRS was mutated to G, D, or E. Steady-state kinetic of aminoacylation, and combined editing assays indicated that not only the size of the amino acid but also the absence of hydrogen bonds between T252 and adjacent molecules may affect the editing. It is further confirmed by in vivo experiments using the temperature-sensitive strain KL231 (DeltaleuS), which revealed the arrested growth of bacterial cells bearing mutants with highly impaired editing activity in the presence of leucine analog.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Min-Gang
authors.initials: MG
authors.lastname: Xu
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Xing
authors.initials: X
authors.lastname: Du
authors.forename: En-Duo
authors.initials: ED
authors.lastname: Wang
mesh_terms: D000215:Acylation; D000255:Adenosine Triphosphate / Q000378:metabolism; D002470:Cell Survival; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D006868:Hydrolysis; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D007935:Leucine-tRNA Ligase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D012356:RNA, Transfer, Leu / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013912:Threonine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D012356:RNA, Transfer, Leu; D011994:Recombinant Proteins; D013912:Threonine; D000255:Adenosine Triphosphate; D007935:Leucine-tRNA Ligase; D007930:Leucine