Grant: Operating Grant

In recent years it has become abundantly clear that microorganisms living within and on humans, also referred to as the 'human microbiome', play a crucial role in human physiology, immunity and nutrition. Although bacteria are by far the most numerous cellular components of the human microbiome, with bacterial cells outnumbering human cells in the body by approximately 10 to 1, bacteriophages (phages), the viruses that infect bacteria, are likely present in even greater numbers. Phages are the major predators of bacteria in most ecological niches on earth and the battle for survival between bacteria and phages is one of the major drivers of bacterial evolution. Furthermore, complete phage genomes, or fragments thereof, are found within the genomes of most bacterial strains and genes expressed from these 'prophages' can profoundly influence bacterial behaviours, particularly pathogenicity. Due to the importance of phages in the ecology of bacteria, understanding the factors that modulate the interactions between bacteria and phages is crucial. Our research is focused on the CRISPR/Cas system of bacteria, which functions as an immune system protecting bacteria against infection by phages and other foreign DNA elements. The CRISPR/Cas system is found in approximately 50% of bacteria and, thus, has a widespread effect on the survival of diverse bacterial species. In our laboratory, we have recently discovered a novel group of proteins that inhibit some types of CRISPR/Cas systems. Our future research is aimed at understanding how these proteins function, determining how widespread these proteins are, and gauging the overall impact of these proteins on the survival and behaviour of bacterial populations.