Abstract
The bacterial flagellum is a complex organelle with many parts that must be assembled in a sequential order. The flagellar and chemosensory network includes more than 60 genes. For many pathogens such as Salmonella, flagella play a crucial role in bacterial virulence. They are required to reach sites of infection and to initiate biofilm formation. Most of the flagellum is assembled outside the cytoplasm and beyond the surface of the cell. This has required the development of mechanisms of self-assembly to over come the formidable problem of building this structure. We have shown that flagellar gene regulation is coupled to assembly at the completion of the flagellar motor: the hook-basal body (HBB). A secreted molecular ruler measure a minimal length for the extracellular hook and then signals the flagellar type III secretion system to change secretion specificity from proteins needed for HBB assembly to filament substrates. A transcriptional inhibitor is also secreted to time gene expression of filament and chemosensory genes to completion of the HBB. I will present evidence for a mechanism of localized transcription and translation that allows for the efficient assembly of the 10,000 subunit external filament.
Biography
I received my Ph.D. in microbial genetics at the University of Utah. My thesis work with John Roth and Baldomero Olivera was on the NAD biosynthetic pathway of Salmonella.
My postdoctoral research was in the lab of Mel Simon at Caltech on the Hin site-specific recombinase that mediates flagellar phase variation in Salmonella
I worked at the University of Washington in Seattle as an Assistant, Associate and Full Professor from 1989 to 2004.
I moved to the University of Utah in 2005 where I am today.
Visiting professorships: University of Konstanz, Germany 1997-1998; University of Osaka, Japan 2005 and 2007; and University of Fribourg, Switzerland 2010-2011
My research involves aspect of bacterial flagellum assembly, gene regulation & type III secretion mechanisms