Talk abstracts

Talk on Saturday 08:30-08:45am submitted by Tammy Bullwinkle

Post-translational modification of a translation factor by a tRNA synthetase paralog

Herve Roy (Ohio State University), Tammy J. Bullwinkle (Ohio State University), William W. Navarre (University of Toronto), Michael Ibba (Ohio State University)

Abstract:
Aminoacyl tRNA-synthetases (aaRSs) are essential for aminacylating tRNAs and thereby providing substrates for ribosomal translation. Several aaRS paralogs of these highly conserved enzymes have been identified across all domains of life and their roles often fall outside tRNA aminoacylation for protein synthesis. Bacterial poxA, which encodes a paralog of type II lysyl tRNA-synthetase (LysRS), is often located near two other genes yjek and efp, encoding a lysine aminomutase and a poorly understood translation factor (EF-P) respectively. These three genes demonstrate strong phenotypic pleiotropy in Salmonella and appear to be needed for efficient translation of a subset of messages during virulence and stress adaptation. Here we show PoxA efficiently modifies EF-P with (R)-beta-lysine, the product of YjeK, by mimicking the activity of LysRS. The modified form of EF-P is able to stimulate peptide bound synthesis on the ribosome suggesting the PoxA/YjeK/EF-P (PYE) pathway regulates bacterial gene expression directly at the level of the ribosomal translation machinery.

Keywords: tRNA synthetase, translation factor EF-P, posttranslational modification