Mentor: Rachel Keener
P.I.: Dennis Ko, M.D., Ph.D.
Yersinia pestis is the causative agent of the plague, and many of its destructive effects on the human body are attributed to its ability to evade and target immune cells. Interestingly, despite the plague’s immunosuppressive capabilities, there is still significant variability in infection outcome. The Ko lab has previously identified a nonsynonymous single nucleotide polymorphism (SNP) located in a functional motif of an immunoreceptor. The minor allele at this locus is associated with decreased bacterial invasion. The extracellular binding region of this transmembrane receptor is made up of Ig-like domains. In order to study where and how the bacterial ligand binds to this receptor, we used restriction enzyme-based cut-and-paste cloning to create mutated versions of this immunoreceptor. Specifically, we removed the Ig-like domains of interest one by one and transfected HeLa cells. Other sites of interest are the tyrosines on immunoregulatory motifs in the intracellular portion of the protein. Site-directed mutagenesis was used to replace tyrosine with phenylalanine to “knockout” the motifs. HeLa cells overexpressing the mutants were then infected with Yersinia pestis. Finally, we used flow cytometry to determine bacterial attachment and invasion for all of these mutants at 4 hours post infection.
