The history of septin biology and bacterial infection.

Investigation of cytoskeleton during bacterial infection has significantly contributed to both cell and infection biology. Bacterial pathogens Listeria monocytogenes and Shigella flexneri are widely recognised as paradigms for investigation of the cytoskeleton during bacterial entry, actin-based motility, and cell-autonomous immunity. At the turn of the century, septins were a poorly understood component of the cytoskeleton mostly studied in the context of yeast cell division and human cancer. In 2002, a screen performed in the laboratory of Pascale Cossart identified septin family member MSF (MLL septin-like fusion, now called SEPT9) associated with L. monocytogenes entry into human epithelial cells. These findings inspired the investigation of septins during L. monocytogenes and S. flexneri infection at the Institut Pasteur, illuminating important roles for septins in host-microbe interactions. In this review, we revisit the history of septin biology and bacterial infection, and discuss how the comparative study of L. monocytogenes and S. flexneri has been instrumental to understand septin roles in cellular homeostasis and host defence.