Eight Stranded β-Barrel and Related Outer Membrane Proteins: Role in Bacterial Pathogenesis

Gram negative bacteria have evolved many mechanisms of attaching to and invading host epithelial and immune cells. In particular, many outer membrane proteins (OMPs) are involved in this initial interaction between the pathogen and their host. This review focuses on a number of small pore-forming OMPs that are all composed of eight-stranded beta- barrel proteins and include members of the OmpA, OmpW and OmpX families of proteins. These proteins, together with the related OmpA-like peptidoglycan associated lipoproteins, are involved in interactions with host cells and are mediators of virulence. In many cases, these proteins interact with host immune cells and can be considered as pathogen associated molecular patterns (PAMPS) due to their ability to signal via Toll like receptor molecules and other pattern recognition receptors. The role of these proteins in pathogenesis is discussed here, together with the potential for these proteins to be used as immunoprophylactic agents to protect against infection.