Studies on the function of the bactericidal type IV secretion systems of Xanthomonadales bacterial species

Abstract

X. citri is only one of hundreds of species in the Xanthomonas genus and several times more species in the order Xanthomonadales that includes important environmental species from soil, water and plant environments. As more and more of the genomes of bacteria from these species are sequenced every year, we are slowly building a clearer picture regarding the extent to which homologs of the X. citri bacteriacidal T4SS is found in other organisms. So far, we have identified homologous systems in species from other Xanthomonadales genera including Stenotrophomonas, Lysobacter, Pseudoxanthomonas, Luteimonas, Luteibacter, Dyella and Rhodanobacter. Interestingly, it seems that this system is not restricted to the Gammaproteiobacteria class, since homologous systems can also be found in some Neisseiria spp and Burkholdeiria spp from the betaproteobacteria class. We are very interested in exploring the structure and function of these homologous systems. In this study, we therefore plan to extend this characterization to some other species in the genera listed above. This characterization includes I) a bioinformatics analysis of the databases in order to obtain specific bacterial strains carrying a seemingly functional bacterial killing T4SS from other research groups or microbiological collections; II) the production of T4SS knockouts in these bacterial species; III) setting up bacterial killing assays using the wild-type and mutant strains, and finally; IV) the expression of the core complexes from these homologous T4SSs for structural analysis using Cryo-EM. (AU)