Center for Cancer Research Seminar
|Event Date:||April 25, 2013|
The family of Opa proteins from Neisseria gonorrhoeae and N. meningitidis are eight-stranded beta-barrel proteins that induce phagocytosis of the bacterium by engaging three different host receptors: carcinoembryonic antigen cellular adhesion molecules (CEACAM), heparansulfate proteoglycans (HSPG), or integrins via HSPG and fibronectin or vitronectin. The receptor engaged depends on the sequence of two of the extracellular loops (termed hypervariable (HV) loop 1 and 2), which are highly variable between isolates. There are multitudes of HV sequences identified; however, only approximately 25 Opa protein sequences have been characterized in terms of receptor engagement. Multiple sequence alignment of the HV loops does not reveal specificity motifs among the family of Opa proteins due to the extreme variability in the amino acid sequences. The solution NMR structure of Opa60 from N. gonorrhoeae that interacts with CEACAM1 receptors to induce phagocytosis reveals that the beta-barrel is a canonical eight-stranded beta-barrel and the HV loops are long, disordered, and highly dynamic. The NMR solution structure, coupled with in vivo Opa reconstituted liposome assays, has facilitated investigations of the molecular determinants of Opa-receptor interactions.
Light refreshments served.