title: Functional association between three archaeal aminoacyl-tRNA synthetases.
abstract: Aminoacyl-tRNA synthetases (aaRSs) are responsible for attaching amino acids to their cognate tRNAs during protein synthesis. In eukaryotes aaRSs are commonly found in multi-enzyme complexes, although the role of these complexes is still not completely clear. Associations between aaRSs have also been reported in archaea, including a complex between prolyl-(ProRS) and leucyl-tRNA synthetases (LeuRS) in Methanothermobacter thermautotrophicus that enhances tRNA(Pro) aminoacylation. Yeast two-hybrid screens suggested that lysyl-tRNA synthetase (LysRS) also associates with LeuRS in M. thermautotrophicus. Co-purification experiments confirmed that LeuRS, LysRS, and ProRS associate in cell-free extracts. LeuRS bound LysRS and ProRS with a comparable K(D) of about 0.3-0.9 microm, further supporting the formation of a stable multi-synthetase complex. The steady-state kinetics of aminoacylation by LysRS indicated that LeuRS specifically reduced the Km for tRNA(Lys) over 3-fold, with no additional change seen upon the addition of ProRS. No significant changes in aminoacylation by LeuRS or ProRS were observed upon the addition of LysRS. These findings, together with earlier data, indicate the existence of a functional complex of three aminoacyl-tRNA synthetases in archaea in which LeuRS improves the catalytic efficiency of tRNA aminoacylation by both LysRS and ProRS.
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, USA. ibba.1@osu.edu
authors.forename: Mette
authors.initials: M
authors.lastname: Praetorius-Ibba
authors.forename: Corinne D
authors.initials: CD
authors.lastname: Hausmann
authors.forename: Molly
authors.initials: M
authors.lastname: Paras
authors.forename: Theresa E
authors.initials: TE
authors.lastname: Rogers
authors.forename: Michael
authors.initials: M
authors.lastname: Ibba
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D049148:Aminoacylation; D019843:Archaeal Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D002384:Catalysis; D007935:Leucine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology; D008250:Lysine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology; D017013:Methanobacteriaceae / Q000201:enzymology* / Q000502:physiology; D025941:Protein Interaction Mapping; D015398:Signal Transduction / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D019843:Archaeal Proteins; D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase; D007935:Leucine-tRNA Ligase; D008250:Lysine-tRNA Ligase