The overall goal of this project is to develop a framework for understanding the way in which membrane proteins expressed on pathogen cell membranes mediate the interactions of pathogens with their human host. We focus on Ail (attachment invasion locus), a protein expressed in the outer cell membrane of the bacterium Yersinia pestis, which is the causative agent of plague. The Y. pestis bacterium is highly pathogenic, spreads rapidly and causes extremely high human mortality. Although it is sensitive to a restricted panel of antibiotics, the potential weaponization of aerolized bacteria with bio-engineered antibiotic resistance and the lack of an effective vaccine or therapy are major concerns, contributing to its classification as a Tier 1 Biothreat Agent. Ail is a key bacterial virulence factor and a prime candidate for therapeutic development due to its functions in mediating bacterial adhesion to host cells, and promoting bacterial resistance to human immunity. This project focuses on elucidating the molecular mechanisms of these key functions of Ail by determining its three-dimensional structure and structurally characterizing the interactions of Ail with its human ligands. These studies will focus on samples of Ail and its complexes incorporated in detergent-free lipid bilayer membranes because the biological activity of Ail is dramatically altered in the presence of micellar detergents. Furthermore, these studies will utilize NMR spectroscopy, a method adept at characterizing both structure and dynamics, because the extracellular loops of Ail that mediate the interactions with host are highly dynamic. Finally, these studies will complement the experimental data generated for Ail in lipid bilayer membranes, by developing computational methods tailored specifically for NMR structural analysis of integral membrane proteins within their functional environment of the phospholipid bilayer membrane. The methods will be designed to facilitate structure determination and increase structural quality, and they will be integrated with widely used programs for programs for NMR structure calculations so as to broaden the impact of our work.

Public Health Relevance

Membrane proteins play fundamental roles in human health and are major targets for therapeutic drug development. Elucidating the structures of bacterial membrane proteins involved in cell adhesion and evasion of the human immune system, as described in this project, will provide information important for advancing medical and pharmaceutical research.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Unknown (R35)
Project #
1R35GM118186-01
Application #
9071833
Study Section
Special Emphasis Panel (ZGM1-TRN-Y (MR))
Program Officer
Chin, Jean
Project Start
2016-06-01
Project End
2021-05-31
Budget Start
2016-06-01
Budget End
2017-05-31
Support Year
1
Fiscal Year
2016
Total Cost
$752,107
Indirect Cost
$366,411
Name
Sanford-Burnham Medical Research Institute
Department
Type
DUNS #
020520466
City
La Jolla
State
CA
Country
United States
Zip Code
92037
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Dutta, Samit Kumar; Yao, Yong; Marassi, Francesca M (2017) Structural Insights into the Yersinia pestis Outer Membrane Protein Ail in Lipid Bilayers. J Phys Chem B 121:7561-7570
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