How cells count: Flagellar regulation in S. typhimurium

Chris Rao, Chemistry, UIUC

Cells, including bacteria, house a number of discrete organelles. While in some cases the cell only needs to build a single copy of a given organelle, in other cases it needs to build many. This latter scenario suggests that cells must employ an active mechanism for sensing and controlling organelle abundance. For, if the cell builds too few, then the integrated activity of these organelles may be insufficient to complete necessary tasks; if the cell builds too many, then critical resources are wasted and, worse, detrimental interactions may occur.

I will discuss our work using the flagellum from /Salmonella/ as a model system for organelle number control. Using a combination of mathematical modeling and experimental analysis, I will demonstrate how /Salmonella/ employs protein secretion as a proxy for flagellar abundance and then uses this signal to dynamically regulate flagellar gene expression.