Bacterial flagellum assembly and coupled gene regulatory mechanisms

Titulo: Bacterial flagellum assembly and coupled gene regulatory mechanisms

Conferenciante: Prof. Kelly T. Hughes (Department of Biology, University of Utah Salt Lake City, USA)

Fecha: viernes, 15 de septiembre de 2017

Horario: 12:00 h

Lugar: Salón de Grados cicCartuja2

Abstract: Many bacteria swim using propeller devices called flagella that rotate at rates up to 60,000 rpm. 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 and nano-scale length control to overcome the formidable problem of building this structure. We have shown that the 22-nm flagellar driveshaft is determined by the length of Braun's lipoprotein, which tethers the outer membrane to the cell wall. 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 measures 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. Transcriptional anti-regulators are also secreted to time the cessation of HBB gene expression and the initiation of filament and chemosensory genes to completion of the HBB.

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