Sample P&F Research Proposal
Project #2 Proposal
TITLE: The role of surface-anchored proteins in Listeria monocytogenes pathogenesis.
INVESTIGATOR: Jess Leber, Ph.D. (Microbiology)
FUNDING PERIOD: 12/1/09 - 11/30/10
DESCRIPTION:
Using a microarray-based in vivo negative selection, my laboratory has identified nine novel cell surface virulence factors required by the intracellular bacterial pathogen Listeria monocytogenes for colonization of the liver in mice. To determine the role these proteins play in L. monocytogenes liver pathogenesis, we will 1) identify L. monocytogenes cell-surface virulence factors necessary for infection of the mammalian liver; 2) determine functions of L. monocytogenes cell-surface virulence factors in initial colonization of the liver; and 3) characterize the host innate immune response to WT and mutants strains of L. monocytogenes.
Project # 2 Progress Report
TITLE: The role of surface-anchored proteins in Listeria monocytogenes pathogenesis
INVESTIGATOR: Jess H. Leber
FUNDING PERIOD: 12/01/09 – 11/30/10
PROGRESS REPORT: With funding provided by this award, we investigated the role of Sortase A-anchored proteins in the pathogenesis of Listeria monocytogenes. Sortase A covalently links the critical invasion- promoting virulence factor Internalin A (InlA) to the peptidoglycan of L. monocytogenes. In addition to InlA, approximately 50 L. monocytogenes proteins contain the canonical LPXTG Sortase A recognition motif, and thus are likely similarly anchored to the bacteria cell surface. On the cell surface, these proteins contribute to the host-pathogen interface, but the role of these putative Sortase A-anchored proteins had not been previously determined.
In a mouse intravenous lethal challenge infection model, we examined the role of Sortase A-anchored proteins to pathogenesis. We determined that Sortase A-deficient bacteria (∆srtA) and Internalin A-deficient bacteria (∆inlA) were equally attenuated for virulence. These data indicate that the major role of Sortase A in L. monocytogenes pathogenesis, in this infection model, is to anchor InlA, and that other Sortase A-anchored proteins do not significantly contribute to pathogenesis.
It remains possible that Sortase A-anchored proteins, in addition to InlA, contribute to aspects of L. monocytogenes pathogenesis that are not tested in our mouse i.v. infection model. Alternately, these other Sortase A substrates might instead contribute to bacterial fitness during saprophytic stages of its lifecycle. Additionally, proteins anchored to the cell surface by Sortase A-independent mechanisms (e.g. GW-motif anchoring) could be more relevant to L. monocytogenes pathogenesis. All of these possibilities will be considered for future studies.
Core Facilities Used: (1) Host-Microbe Core (2) Tissue and Cell Analysis Core
GRANTS:
Received: Great Lakes Region Center of Excellence Career Development Award 03/01/10 – 02/28/12 ($110,000 per year)
Submitted: NIH RO1
04/01/12 – 03/31/17 ($225,000 per year)
PUBLICATIONS:
Quillin, S.J., Schwartz, K.T., and Leber, J.H. (2011) The novel Listeria monocytogenes bile sensor BrtA regulates expression of the cholic acid efflux pump MdrT. Molecular Microbiology, 81 (1): 129-42. PMID: 21542862.
Please acknowledge support from the DDRCC (NIDDK P30DK42086) in your publications and presentations.