Poster abstracts
Poster number 59 submitted by Sarah Venus
Interactions with Vaccinia Virus K7 Protein Alter the Biochemical Activity of the DEAD-Box RNA Helicase DDX3X
Sarah Venus (Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH), McKenzie Clapp (Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH), Andrea Putnam (Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH), Eckhard Jankowsky (Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH)
Abstract:
The DEAD-box RNA helicase DDX3X, which functions in translation initiation and cellular signaling, is targeted by proteins from diverse viruses, including K7, a protein from the poxvirus vaccinia. K7 binds the N-terminus of DDX3X, a region that facilitates oligomerization of DDX3X as well as association with translation initiation factors and stress granules. The impact of K7 on DDX3X’s biochemical activities and roles in RNA metabolism is unknown. We show that K7 inhibits ATP-dependent RNA duplex unwinding activity of DDX3X, but simultaneously promotes DDX3X-mediated ATP hydrolysis. K7 shows similar effects on the S. cerevisiae DDX3X ortholog Ded1p, which shares the N-terminal K7 binding site. Since monomeric Ded1p exhibits higher ATPase, but lower unwinding activity compared to oligomeric Ded1p, our results suggest that K7 impacts the oligomerization of DDX3X and Ded1p. We further show formation of recombinant DDX3X granules in vitro. This allows direct visualization of K7’s effect on DDX3X oligomerization and granule formation. Ultimately, characterizing the interaction between K7 and DDX3X will provide insight into strategies by which viruses target DDX3X to alter RNA metabolism in the host.
Keywords: DDX3X, Granules, K7