Research SummaryStudies towards the role of Staphylococcal Pathogenicity Island (SaPI) in adaptation and virulence of Staphylococcus aureus
Staphylococcus aureus (S. aureus) is a pathogenic bacterium that can infect any organ of the human body. It’s one of the most successful pathogens, having remarkable adaptability and virulence. S. aureus strains can carry different mobile genetic elements (MGEs), including plasmids, transposons, staphylococcus cassette chromosomes (SCC), bacteriophages and staphylococcal pathogenicity islands (SaPIs), which contribute to their virulence, broad host range and antibiotic resistance. Horizontal transfer of MGEs among different S. aureus strains plays a vital role in the evolution of this pathogen.
SaPIs are highly mobile chromosomal islands that are induced to excise and replicate by specific phages, “helper phages”. The SaPI replicated DNA is packaged in phage-encoded particles and released upon phage-mediated lysis. These islands, often carry unique toxin genes, move readily between strains, mediate transfer of unlinked chromosomal genes and interfere with the reproduction of the very phages they parasitize. All sequenced genomes of naturally occurring staphylococcal strains contain at least one intact or defective SaPI.
I propose that the diversity, adaptability and virulence of this notorious pathogen depend greatly on its extraordinary islands (SaPIs). The focus of my research proposal is these incredible islands. An understanding of their biology and capabilities will enable us to modify the SaPI and consequently reduce the severity and spread of staphylococcal infection. The proposed research focuses on SaPI’s complex role in HGT, in staphylococcal genomic plasticity and in the metamorphosis of this infamous pathogen.
Figure Legend: SaPI Life Cycle; SaPIs are highly mobile chromosomal islands that are induced to excise and replicate by specific phages, “helper phages”. The SaPI replicated DNA is packaged in phage-encoded particles and released upon phage-mediated lysis. Particles containing SaPI genome are transferred at very high frequencies comparable to those containing phage genome.