The Role of Septins during Invasion of Host Cells by Salmonella enterica serovar Typhimurium

Salmonella enterica serovar Typhimurium (S. Typhimurium) initiates invasion of host cells using a Type 3 Secretion System to translocate bacterial virulence proteins (known as effectors) across the host cell plasma membrane. The effectors manipulate host cell machinery to induce actin cytoskeleton rearrangements that lead bacteria internalization. Previous studies have demonstrated the importance of host actin interactors in bacterial invasion, but how these factors are dynamically coordinated remains unclear. In my thesis, I demonstrate that septins, a conserved family of GTPases, are recruited to sites of bacterial invasion and are required for efficient bacterial internalization. Septins also promote recruitment of ROCKII kinase to invasion sites and its downstream activation of the actin nucleating protein FHOD1. In contrast, myosin II activation, known to be required for S. Typhimurium invasion, was not septin-dependent. Collectively, my data provide new insight into the mechanisms by which host actin regulatory proteins contribute to S. Typhimurium invasion.M.Sc.2018-11-29 00:00:0