Research Topics
Species | ACTIN BASED MOTILITY OF A BACTERIAL PATHOGENSummaryPrincipal Investigator: Julie Theriot Abstract: Listeria monocytogenes is a ubiquitous Gram-positive bacterium that can cause serious food-borne infections in pregnant women, newborns and immunocompromised adults. The bacterium grows directly in the cytoplasm of infected host cells and moves rapidly throughout and between infected cells using a form of actin-based motility. The L. monocytogenes surface protein, ActA, is expressed in a polarized fashion and interacts with host cell cytoskeletal factors to induce the polymerization of an actin "comet tail" structure that pushes the bacterium through the host cell cytoplasm. The overall goal of this project is to understand the mechanism and biological significance of the actin-based motility of L. monocytogenes. We use a combination of three complementary approaches to studying this form of motility-biophysical, biochemical, and cell biological. The full set of basic protein components required for actin-based motility by L. monocytogenes have now been identified and the field is beginning to agree on a general physical framework for understanding force generation during steady-state movement. The next set of conceptual and experimental challenges lie in rebuilding and coming to grips with the mechanisms underlying the full complexity of the biological behavior. We will focus our mechanistic studies on bacterial actin-based motility in two areas that are not adequately addressed by the existing steady-state models: understanding the biochemical and biophysical mechanism of bacterial movement initiation and exploring the determinants responsible for regulating path persistence and curvature. In examining the cell biology of infection in the context of bacterial cell-to-cell spread, we will develop new techniques for direct observation of bacterial spread in fully polarized epithelial monolayers in tissue culture and heterotypic spread between epithelial cells and macrophages. In addition, we will address the cell biology of the bacterial cell in determining the mechanism of ActA protein polarization. Successful completion of our research goals would give significant insight into the mechanisms by which pathogenic bacteria such as L. monocytogenes communicate specifically with the cells of their human hosts. In addition, since L. monocytogenes actin-based motility is a simple model system for force generation by actin polymerization, the results of our research would contribute to our understanding of a wide variety of basic biological processes involving actin-based cell movement, including wound healing, inflammation, embryonic development, and cancer metastasis. Funding Period: 1994-12-01 - 2010-02-28 more information: NIH RePORT Top Publications
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Choosing orientation: influence of cargo geometry and ActA polarization on actin comet tailsCatherine I Lacayo
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
Mol Biol Cell 23:614-29. 2012....- Bacterial shape and ActA distribution affect initiation of Listeria monocytogenes actin-based motilitySusanne M Rafelski
Department of Biochemistry, Stanford University Medical Center, Stanford, California 94305 5307, USA
Biophys J 89:2146-58. 2005..Over time, saltatory motility and sensitivity to the immediate environment decreased as bacterial movement became robust at a constant steady-state speed... - Adhesion controls bacterial actin polymerization-based movementFrederick S Soo
Department of Physiology and Biophysics, University of Washington, Seattle, WA 98105, USA
Proc Natl Acad Sci U S A 102:16233-8. 2005..The idea that speed depends on adhesion, rather than polymerization, suggests several alternative mechanisms by which known cytoskeletal regulatory proteins could control cellular movement... - Mechanism of polarization of Listeria monocytogenes surface protein ActASusanne M Rafelski
Department of Biochemistry, Stanford University Medical Center, 279 W Campus Dr, Stanford, CA 94305 5307, USA
Mol Microbiol 59:1262-79. 2006.... - Listeria monocytogenes traffics from maternal organs to the placenta and backAnna I Bakardjiev
Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California, USA
PLoS Pathog 2:e66. 2006..Once colonized, the placenta becomes a nidus of infection resulting in massive reseeding of maternal organs, where L. monocytogenes cannot be cleared until trafficking is interrupted by expulsion of the infected placental tissues... - Close packing of Listeria monocytogenes ActA, a natively unfolded protein, enhances F-actin assembly without dimerizationMatthew J Footer
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
J Biol Chem 283:23852-62. 2008....