Analysis of the Role of the TAT Protein Translocation System in Campylobacter Jejuni

Many of the primary dehydrogenases and terminal reductases in the electron transport chains of Campylobacter jejuni possess a "twin-arginine" translocase (TAT) recognition motif, indicating that protein export by the TAT system may be crucial in the respiratory physiology of C. jejuni. However, in other bacteria it is now clear that the functions of the TAT system extend far beyond the assembly of electron transport chains, to include cell wall biosynthesis, adaptation to different growth conditions and virulence. We have identified a significant number of additional potential TAT substrates in C. jejuni, and now wish to understand the wider importance of the TAT system in this pathogen. In preliminary work we have constructed a tatC mutant and have characterised several novel TAT substrates. <P>
In this project we will:<OL> <LI> Determine the consequences of the loss of the TAT system, by a detailed analysis of the phenotype of tatA and tatC mutants<LI> Undertake a proteomic analysis of wild-type and tat mutant strains, to identify TAT substrate proteins and compare with predictions from the genome sequence and to determine the global effects of protein mislocalisation in tat mutants<LI> Investigate the physiological functions of a small selection of putative TAT substrates by a combination of mutageneis and biochemical characterisation of heterologously expressed protein.