Creating a chimera: Studying multiple sclerosis through a myelin basic protein-actin fusion protein

CHED 807

Jessica Fox Bruhn and Douglas H Juers, juersdh@whitman.edu. Department of Physics, Whitman College, 345 Boyer Ave, Walla Walla, WA 99362
Multiple sclerosis is a chronic neurodegenerative disease involving an autoimmune attack against myelin proteins, including myelin basic protein (MBP). Knowing the three-dimensional structure of MBP would provide configurational information about MBP epitopes, and could help to identify homologous proteins that may trigger the autoimmune response. MBP has been difficult to crystallize, partly because it is unstructured in the absence of interaction partners, which are known to include actin, Ca2+-calmodulin, tubulin and clathrin. We hope to utilize the interaction between actin and MBP to stabilize a folded form of MBP and promote crystallization of an actin-MBP complex. To lower the entropic cost of crystallization, we created a chimeric protein by connecting the 18.5 kDa isoform of human MBP to human β-actin actin by a flexible five amino acid linker. The MBP-actin chimera showed improved expression over MBP alone. We will present the results from our efforts to optimize the expression, purify and characterize this chimeric MBP-actin protein.