title: In vivo characterization of an Hfq protein encoded by the Bacillus anthracis virulence plasmid pXO1.
abstract: Bacterial Hfq proteins post-transcriptionally regulate gene expression, primarily by mediating the interaction between sRNAs (small RNAs) and their target mRNAs. The role of Hfq-based regulation has been well defined in Gram-negative bacteria, but comparatively less is known about the impact of Hfq proteins in Gram-positive species. The Gram-positive pathogen Bacillus anthracis (causative agent of anthrax) is distinct in that it expresses three homologs of Hfq: Hfq1 and Hfq2 from the chromosome, and Hfq3 from the pXO1 virulence plasmid.
  
  
  
  In this study, we utilized overexpression as a strategy to examine the impact of Hfq3 on B. anthracis physiology. The increase in Hfq3 protein levels led to anomalous cell shape and chain formation, which manifested as a severe growth defect. This phenotype was specific to B. anthracis, as Hfq3 expression in B. subtilis at similar levels was not toxic. Toxicity was dependent on residues on the distal face of Hfq3 that are involved in mRNA binding in other bacterial species.
  
  
  
  Thus, we hypothesize that Hfq3 interacts with RNA(s) involved in essential functions in the B. anthracis cell, leading to increased binding upon overexpression that either sequesters or accelerates degradation of RNAs important for growth. These results not only aid in elucidating the role of Hfq proteins in B. anthracis, but also contribute to our current understanding of Hfq in Gram-positive bacteria.
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Keefer
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.|Department of Biology, Frostburg State University, Frostburg, MD, USA.
authors.forename: Eugenia K
authors.initials: EK
authors.lastname: Asare
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Pomerantsev
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Mahtab
authors.initials: M
authors.lastname: Moayeri
authors.affiliation: Genomics Unit, Research Technologies Section, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Martens
authors.affiliation: Genomics Unit, Research Technologies Section, Rocky Mountain Laboratories, NIAID, NIH, Hamilton, MT, USA.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Porcella
authors.affiliation: National Cancer Institute, NIH, Bethesda, MD, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Gottesman
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
authors.affiliation: National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Bethesda, MD, USA. catherine.vrentas@ars.usda.gov.|National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, IA, USA. catherine.vrentas@ars.usda.gov.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Vrentas
mesh_terms: D000818:Animals; D000881:Anthrax; D001329:Autolysis; D001408:Bacillus anthracis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D005822:Genetic Vectors; D035001:Host Factor 1 Protein / Q000235:genetics* / Q000378:metabolism*; D034982:Integration Host Factors / Q000235:genetics; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D010957:Plasmids / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics*
chemical_list: D035001:Host Factor 1 Protein; D034982:Integration Host Factors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011994:Recombinant Proteins
keywords: Bacillus anthracis; Hfq; anthrax; gene expression; mRNA; pXO1; sRNA