Pathogens use some pretty awesome tricks in order to replicate in and infect cells. Today’s image is of a bacterial pathogen that exploits the actin cytoskeleton in its host cell.
Rickettsia are bacterial pathogens, and many Rickettsia species are able to co-opt its host cell’s actin cytoskeleton for its own motility within and between cells during infection. Rickettsia assemble “comet tails” that are made of parallel actin filament arrays, and these structures propel them in the direction they need to go. A recent paper found that a bacterial protein called Sca2 promotes actin filament assembly, and is found on the surface of the bacteria. Images above show Rickettsia in cell extracts with Sca2 (white or green) and actin (white or purple) labeled. Zoomed images (bottom) are of the bacterium in the lower left hand corner (top).
Adapted by permission from Macmillan Publishers Ltd, copyright 2010.Haglund CM, Choe JE, Skau CT, Kovar DR, & Welch MD (2010). Rickettsia Sca2 is a bacterial formin-like mediator of actin-based motility. Nature cell biology, 12 (11), 1057-63 PMID: 20972427