title: Regulation and RNA-binding properties of Hfq-like RNA chaperones in Bacillus anthracis.
abstract: BACKGROUND
  Small RNAs (sRNAs) are important modulators of gene expression in bacteria. Regulation by sRNAs is yet to be established in Bacillus anthracis. Here, regulation and RNA-binding properties of Hfq-like RNA chaperones in B. anthracis are investigated.
  
  
  METHODS
  Transcript levels were measured by RT-PCR. Proteins were cloned, purified, and their ability to bind sRNA was seen by EMSA. Regulators of Hfq1 were identified by in silico analysis and validated by EMSA. Conserved sRNAs were identified by homology search and their ability to bind Hfq1 was seen by EMSA. Residues crucial for sRNA binding were identified by mutational studies.
  
  
  RESULTS
  hfq1 and hfq3 showed expression during exponential phase on BHI medium, while hfq2 showed no expression. Hfq1 and Hfq3 formed hexamer and sRNA-Hfq complex, not Hfq2. In silico prediction and EMSA confirmed AbrB binding to the promoter of Hfq1. Homology search identified 7 sRNAs in B. anthracis. The sRNA CsfG showed binding to Hfq1 via residues Y24, F29, Q30, R32, K56, and H57.
  
  
  CONCLUSIONS
  Hfq1 and Hfq3 can function as RNA chaperones in B. anthracis. The transition phase repressor AbrB might be responsible for the growth-dependent expression of Hfq1. The sporulation-specific sRNA CsfG binds to Hfq1 via its distal surface and requires an intact hexameric structure for forming CsfG-Hfq1 complex.
  
  
  CONCLUSIONS
  This is the first report demonstrating the regulation and functional properties of Hfq-like RNA chaperones in B. anthracis and paves the path towards establishing sRNA-based regulation in B. anthracis.
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India; Bioinformatics Section, Department of Computer Sciences, Hamdard University, New Delhi 110062. Electronic address: guruduttapanda@gmail.com.
authors: Gurudutta
authors: G
authors: Panda
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Pooja
authors: P
authors: Tanwer
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Salim
authors: S
authors: Ansari
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Devanshi
authors: D
authors: Khare
authors: School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: rakeshbhatnagar@jnu.ac.in.
authors: Rakesh
authors: R
authors: Bhatnagar
mesh_terms: D001408:Bacillus anthracis / Q000235:genetics*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D035001:Host Factor 1 Protein / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism*
chemical_list: D035001:Host Factor 1 Protein; D018832:Molecular Chaperones; D012329:RNA, Bacterial
keywords: AbrB; Bacillus anthracis; CsfG; Hfq; RNA chaperones; Small RNAs