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Hfqs and Small RNA Regulation in Bacillus anthracis: Protein Biochemistry and Transcriptomic Perspectives

Monday, September 22, 2014 — Poster Session II

4:00 p.m. – 6:00 p.m.

FAES Academic Center




  • CE Vrentas
  • S Porcella
  • Z Hu
  • R Ghirlando
  • SH Leppla


Homohexameric bacterial Hfq proteins regulate gene expression via binding of small RNAs (sRNAs) and/or mRNAs. While the role of Hfq in virulence has been characterized in Gram-negative pathogens, its role in Gram-positive pathogens is less clear. Bacillus anthracis is unusual in that it expresses multiple Hfq variants: two chromosomal (Hfq1,2) and one on the pXO1 virulence plasmid (Hfq3). Combined with our discovery of two sRNAs (sRNA-I and sRNA-II) inducibly expressed from pXO1, this prompted our investigation of the role of Hfqs in B. anthracis. The Hfq proteins were produced in E. coli (Hfq1,2) or by cell-free expression (Hfq3). Consistent with its high sequence conservation, Hfq2 is hexameric; unexpectedly, Hfq1 and Hfq3 were monomeric. Reversion of sequence variations in Hfq1 did not restore hexamers, suggesting that its shortened C-terminal tail may cause instability. Expression of Hfq1 in E. coli disrupts Hfq-dependent regulation, consistent with the hypothesis that Hfq1 could play an anti-Hfq role in vivo. Next, the roles of Hfq, sRNA-I, and sRNA-II were examined by RNA-Seq, identifying sRNAs and mRNAs changing in abundance upon deletion of each gene in B. anthracis. Preliminary results will be presented to identify physiological roles of each gene and delineate the pool of Hfq-regulated sRNAs.

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