The bacterial cell envelope is a remarkable and complex structure that guards bacteria from their surrounding environment. A defining feature of Gram-negative bacteria is the presence of an outer membrane that encapsulates the peptidoglycan layer of these organisms. While the inner membrane is composed of glycerophospholipids, the outer membrane is a unique, asymmetric bilayer with glycerophospholipids confined to the inner leaflet and lipid A, a unique saccharolipid, localized to the outer leaflet. Lipid A is the lipid moiety of lipopolysaccharide (LPS) and anchors LPS to the bacterial surface. Bacteria have evolved various mechanisms to adapt to their unpredictable and often hostile surroundings, including strategies for remodeling their membrane architecture. Often these modifications provide resistance to components of the mammalian innate immune system and modulate host recognition of the invading microorganism. The lipid A domain of LPS is toxic to humans and potent stimulator of the innate immune system through via recognition by TLR4- MD2. A number of Gram-negative pathogens modify their lipid A structure to evade host detection. Additionally, structural alteration of lipid A and glycerophospholipids can directly impact bacterial resistance to innate immune effectors such as host antimicrobial peptides. The overall objective of this proposal is to unravel the molecular mechanisms by which Vibrio cholerae, the causative agent of the disease cholera, remodels it membrane architecture and the role this remodeling plays in virulence.
The Specific Aims of the current proposal are: (1) biochemical and genetic analysis of glycine modification of V. cholerae LPS;(2) Biochemical and genetic analysis of phosphoethanolamine modification of V. cholerae LPS;(3) elucidation of machinery required for phospholipid remodeling in V. cholerae;and (4) impact of V. cholerae membrane remodeling on the host innate immune response. The completion of these Aims will directly contribute to our understanding of how lipid remodeling/modification machinery impacts pathogenesis. Finally, from this work will come not only a better understanding of the disease cholera, but new avenues for vaccine development and the ability to generate engineered LPS structures that could serve as potential adjuvants and/or LPS antagonists.
Gram-negative bacteria are responsible for a number of human infectious diseases. This includes bacteria such as Salmonella, Escherichia coli, Pseudomonas, Helicobacter pylori, and Vibrio cholerae. On the surface of these bacteria is a unique molecule called lipopolysaccharide or LPS. Much like armor, LPS helps to protect the bacterium from their surrounding environment. LPS is toxic to humans and activates the immune response. Often, gram-negative bacteria modify their LPS structure to evade detection and resist various defenses of the immune system. This application will help determine how bacteria associated with human disease modify their LPS structure possibly leading to novel therapies.
|Henderson, Jeremy C; Herrera, Carmen M; Trent, M Stephen (2017) AlmG, responsible for polymyxin resistance in pandemic Vibrio cholerae, is a glycyltransferase distantly related to lipid A late acyltransferases. J Biol Chem 292:21205-21215|
|Herrera, Carmen M; Henderson, Jeremy C; Crofts, Alexander A et al. (2017) Novel coordination of lipopolysaccharide modifications in Vibrio cholerae promotes CAMP resistance. Mol Microbiol 106:582-596|
|Band, Victor I; Crispell, Emily K; Napier, Brooke A et al. (2016) Antibiotic failure mediated by a resistant subpopulation in Enterobacter cloacae. Nat Microbiol 1:16053|
|Boll, Joseph M; Crofts, Alexander A; Peters, Katharina et al. (2016) A penicillin-binding protein inhibits selection of colistin-resistant, lipooligosaccharide-deficient Acinetobacter baumannii. Proc Natl Acad Sci U S A 113:E6228-E6237|
|Morrison, Lindsay J; Parker, W Ryan; Holden, Dustin D et al. (2016) UVliPiD: A UVPD-Based Hierarchical Approach for De Novo Characterization of Lipid A Structures. Anal Chem 88:1812-20|
|Henderson, Jeremy C; Zimmerman, Shawn M; Crofts, Alexander A et al. (2016) The Power of Asymmetry: Architecture and Assembly of the Gram-Negative Outer Membrane Lipid Bilayer. Annu Rev Microbiol 70:255-78|
|Chen, Linxiao; Valentine, Jenny L; Huang, Chung-Jr et al. (2016) Outer membrane vesicles displaying engineered glycotopes elicit protective antibodies. Proc Natl Acad Sci U S A 113:E3609-18|
|Petrou, Vasileios I; Herrera, Carmen M; Schultz, Kathryn M et al. (2016) Structures of aminoarabinose transferase ArnT suggest a molecular basis for lipid A glycosylation. Science 351:608-12|
|Eshghi, Azad; Henderson, Jeremy; Trent, M Stephen et al. (2015) Leptospira interrogans lpxD Homologue Is Required for Thermal Acclimatization and Virulence. Infect Immun 83:4314-21|
|Hutterer, Corina; Eickhoff, Jan; Milbradt, Jens et al. (2015) A novel CDK7 inhibitor of the Pyrazolotriazine class exerts broad-spectrum antiviral activity at nanomolar concentrations. Antimicrob Agents Chemother 59:2062-71|
Showing the most recent 10 out of 52 publications