Researchers Discover New Mechanism for Type IV Pili Retraction in Vibrio cholerae

Type IV pili, essential for many pathogens to cause disease, are hair-like appendages that grow out of and are retracted back into bacteria cells, enabling them to move and adhere to surfaces. Although pathogenic bacteria often rely on a specialized molecular motor to retract their pili, a new study, published online on December 19, 2016 in PLOS Pathogens, reveals that a minor pilin protein elicits pilus retraction in the cholera bacterium, Vibrio cholerae. The open-access PLOS Pathogens article is titled “The Vibrio cholerae Minor Pilin TcpB Initiates Assembly and Retraction of the Toxin-Coregulated Pilus.” Bacteria utilize a number of highly sophisticated molecular tools to colonize their hosts. One of the most ubiquitous of these tools is a complex nanomachine called the Type IV pilus. This nanomachine has as few as 10 to as many as 30 molecular components, producing exquisitely thin filaments that extend from the bacterial surface and that can be several times the length of the bacterium itself. These pilus filaments have a remarkable array of functions that rely on their ability to (i) adhere to many substrates, including host cell surfaces, pili from nearby bacteria, DNA and bacterial viruses (bacteriophage), and (ii) to depolymerize or retract, which pulls the bacteria along mucosal surfaces, pulls them close together in protective aggregates, and can even draw in substrates like DNA and bacteriophage for nutrition and genetic variation. In collaboration with researchers from Dartmouth College and Simon Fraser University, Dr. Nicolas Biais, Assistant Professor of Biology at Brooklyn College, City University of New York (CUNY), developed an assay in his laboratory that revealed for the first time that the V.
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