The Yersinia pestis type III secretion system (T3SS) functions to inject anti-host proteins, termed Yops, directly into the cytoplasm of targeted eukaryotic cells. The injection process can be divided into three distinct steps: (i) attachment of the bacteria to a eukaryotic cell;(ii) secretion of Yops across the bacterial inner and outer membranes;and (iii) translocation of Yops across a eukaryotic membrane. Work in our laboratory supported by this Grant has focused on the regulation of the T3S process. Yop secretion is triggered by contact with a eukaryotic cell in vivo or by growth in the absence of extracellular calcium in vitro. A cytosolic YopN/SycN/YscB/TyeA complex is required to block Yop secretion in the presence of calcium and prior to contact with a eukaryotic cell. The mechanism by which the bacterium senses these extracellular signals and transmits this information to the cytosolic compartment is not known. We have recently demonstrated that the surface-localized YscF needle is required to regulate Yop secretion. We hypothesize that the YscF needle and needle-associated proteins (the LcrV needle tip complex and Yscl rod structure) function, in part, to sense extracellular signals, transmit this information to the cytosolic compartment and regulate the activity of a molecular plug (the YopN/SycN/YscB/TyeA complex). The proposed research is aimed at gaining a better understanding of the regulatory events that control Yop secretion. Specifically, we will (i) elucidate the molecular mechanism by which the YopN/SycN/YscB/TyeA complex blocks secretion and (ii) investigate the role of the Yscl rod, the YscF needle and the LcrV tip complex in the regulation of Yop secretion. These studies will advance our understanding of the molecular events that regulate T3S in Y. pestis and in other important pathogens.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI039575-13
Application #
7635737
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Mukhopadhyay, Suman
Project Start
1996-06-01
Project End
2012-05-31
Budget Start
2009-06-01
Budget End
2010-05-31
Support Year
13
Fiscal Year
2009
Total Cost
$375,233
Indirect Cost
Name
University of Miami School of Medicine
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
052780918
City
Coral Gables
State
FL
Country
United States
Zip Code
33146
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