Poster abstracts

Poster number 123 submitted by Kimberly Stanek

Structural and functional characterization of an Aquifex Hfq homolog

Kimberly Stanek (Chemistry, University of Virginia), Jennifer Patterson, Peter Randolph (Chemistry, University of Virginia), AhnThu Nguyen (Biology, University of Virginia), Andrew Holmes (Biomolecular Engineering, University of California Santa Cruz), Todd Lowe (Biomolecular Engineering, University of California Santa Cruz), Cameron Mura (Chemistry, University of Virginia)

Abstract:
The host factor Hfq, as the bacterial branch of the Sm protein superfamily, is an RNA-associated protein that functions in transcript-level regulation of gene expression and mRNA turnover. Hfq acts as an RNA chaperone by facilitating the interactions between mRNAs and small, regulatory noncoding RNAs (sRNAs). Hfq has been shown to form homohexameric rings that feature two distinct faces for RNA-binding. An Hfq homolog has been bioinformatically identified in the genome of the deep-branching thermophile Aquifex aeolicus (Aae), but little is known about its function or structure. Others have demonstrated that Aae Hfq does not complement Hfq-deletion strains of Salmonella enterica, suggesting an independent mechanism of action for Aae Hfq. To elucidate the structure and function of Aae Hfq, we have cloned, over-expressed, purified, crystallized, and biochemically characterized this protein, in vitro and in vivo. We recently determined the crystal structure of Aae Hfq to 1.5 Å resolution. Using fluorescence polarization assays, binding affinities have been determined for the interactions of this Hfq with U- and A-rich RNAs. Notably, recombinant Aae Hfq co-purifies with a collection of small endogenous RNAs; we have recently isolated and characterized these species via RNA-Seq.

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Keywords: Hfq, Crystallography, RNA-protein interactions