Helicobacter pylori is a Gram negative, microaerophilic gastric pathogen that infects nearly 50% of the human population. It is the sole pathogen able to colonize the stomach, and has been closely linked to duodenal and gastric ulcers and adenocarcinomas. The bacterium has been listed as a Group 1 carcinogen by the World Health Organization. The CagA cytotoxin of H. pylori is translocated into host cells by a Type IV Secretion System, interacts with many cellular proteins, increases virulence, and is associated with an increased risk of cancer. CagA has been shown to manipulate many host cellular functions, including cytoskeletal function, cell- to-cell adhesion, and intracellular signl transduction. However, how CagA functions has remained mostly a mystery for nearly two decades. Preliminary data from our laboratory is changing this situation. We have determined high-resolution crystal structures of CagA bound to host targets, have identified stable, soluble subdomains of this large cytotoxin, and have identified novel host factors that interact with these subdomains. This application proposes to perform biochemical, structural, and infection biological studies of these identified subdomains and their interactions with host factors.
The specific aims are (1) to identify, biochemically and structurally characterize the CagA functional subdomains, and (2) to identify, biochemically and structurally characterize the CagA-host factor interactions. Expected outcomes include obtaining detailed crystal structures of CagA host factor interactions, biochemical characterization of the nature of these interactions, and the role of the interactions in modulating host cell biology. Such data will greatly enhance our understanding of virulence, as well as Helicobacter driven carcinogenesis.

Public Health Relevance

The bacterium Helicobacter pylori infects one out of every two people in the world, and is linked to stomach cancer. Helicobacter pylori injects the CagA protein into stomach cells, which deregulates many functions of the infected cell. We propose to isolate the interactions CagA makes with human proteins, and image them at the molecular level to understand how CagA functions. Such an understanding will be the first step in unraveling CagA mediated-virulence and contributions to human cancers.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI098109-02
Application #
8503595
Study Section
Macromolecular Structure and Function C Study Section (MSFC)
Program Officer
Mills, Melody
Project Start
2012-07-15
Project End
2014-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
2
Fiscal Year
2013
Total Cost
$238,995
Indirect Cost
$97,995
Name
Rockefeller University
Department
Microbiology/Immun/Virology
Type
Other Domestic Higher Education
DUNS #
071037113
City
New York
State
NY
Country
United States
Zip Code
10065
NeŇ°i?, Dragana; Buti, Ludovico; Lu, Xin et al. (2014) Structure of the Helicobacter pylori CagA oncoprotein bound to the human tumor suppressor ASPP2. Proc Natl Acad Sci U S A 111:1562-7