whereRU: Aresty Poster 66 - EVOLUTION OF A NOVEL GENE PAIR FROM A PROTEIC TOXIN-ANTITOXIN MODULE by Aresty Posters 2009

EVOLUTION OF A NOVEL GENE PAIR FROM A PROTEIC TOXIN-ANTITOXIN MODULE IN ESCHERICHIA COLI

Abstract

Possible remnants of a new Protein X-Protein Y Toxin-Antitoxin (TA) system have been discovered in E. coli by our lab. In our hypothetical Toxin-Antitoxin System, Protein Y (PY) resembles a toxin as it is associated with the cold-shock response. PY binds to the ribosome through the 30S ribosomal subunit at the 50S-30S subunit interface and prevents ribosome dissociation. During cold-shock, PY blocks the peptidyl-tRNA site and part of the aminoacyl-tRNA site of the ribosome and inhibits protein synthesis. Protein X (PX) is located upstream of Protein Y, and PX possesses many characteristics inherent to the antitoxins. Yet, this hypothetical PX-PY TA system has certain unusual features as the b2596 gene coding for PX produces a leaderless mRNA, lacking a Shine-Dalgarno sequence and possessing an atypical UUG start codon. Although the rare start codon and the lack of an mRNA leader sequence strongly suggest that the b2596 gene no longer encodes a functional mRNA for the PX antitoxin, it also leaves an evolutionary clue that the yfiA-b2596 TA system could have been functional in the past. We are investigating this possibility by studying whether Protein X and Protein Y are capable of interacting with each other.