Mistranslation and Stress Tolerance in E.Coli

Abstract

Mistranslation i.e. translation errors are much more frequent than errors at the replication or transcription level. These errors take place despite having many proofreading mechanisms in place. Thus it is debated whether mistranslation is harmful or beneficial to the cell and there has been evidence on both sides. Recent studies have shown that mistranslation can be beneficial especially under stress. Work in the lab has shown that strains with depleted initiator tRNA content mistranslate by -1 frameshifting and non AUG initiation, and have benefit under short term stress. In this study we are trying to see whether this mistranslating strain has any benefit as compared to the WT strain in long term constant and fluctuating antibiotic stress. To do this we evolved these two strains under antibiotic stress. We then looked at the growth rate increase, resistance increase and the pattern in mutations in the target genes of the evolved strains. We saw differences in the mutations that the WT and the mistranslating mutant show across stress regimes. From this data we can say that the WT and mutant rapidly show an increase in their growth rate and in this course they follow different mutational trajectories. Currently we are studying if there are differences in frameshifting between the two strains. We have created a data set with several controls (hyperaccurate, hypoaccurate and kasugamycin) with the evolution lines and further sequence analysis will reveal the mechanisms used by mistranslation in adaptation to long term and fluctuating stress.