Talk abstracts

Talk on Friday 08:50-09:10pm submitted by Corinne Hausmann

Functional association between three archaeal aminoacyl-tRNA synthetases

Corinne Hausmann (Department of Microbiology, The Ohio State University), Mette Praetorius-Ibba (Department of Radiology, The Ohio State University), Molly Paras (Department of Microbiology, The Ohio State University), Mike Ibba (Department of Microbiology, The Ohio State University)

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 remains largely unknown. Associations between aaRSs have also been reported in archaea, including a complex between prolyl- and leucyl-tRNA synthetases (ProRS, LeuRS) in Methanothermobacter thermautotrophicus. 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 comparable KDs of about 0.3 - 0.9 uM, further supporting the formation of a stable multi-synthetase complex. The steady-state kinetics of aminoacylation by LysRS indicated that LeuRS specifically reduces the Km for tRNALys over 3-fold, with no additional change seen upon addition of ProRS. No significant changes in the kinetics of aminoacylation by LeuRS or ProRS were observed upon 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.

Keywords: aminoacyl-tRNA synthetase