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SUMMARY:Regulatory RNAs in the pathogenic Epsilonproteobacteria Helicobact
 er and Campylobacter
DTSTART:20150519T121500
DTEND:20150519T131500
DTSTAMP:20261002T033647Z
UID:3089891d1a2b1d533328cdf8b3dcb85ff031bf95c9ba14a46fc8f910
CATEGORIES:Conferences - Seminars
DESCRIPTION:Cynthia M. Sharma\nSmall regulatory RNAs (sRNAs) are an emergi
 ng class of posttranscriptonal gene expression regulators that have been i
 mplicated in bacterial stress response and virulence control. The majority
  of the functionally characterized sRNAs act as antisense RNAs on mRNAs. A
 lthough genome-wide approaches have revealed hundreds of sRNA candidates i
 n diverse prokaryotes\, most of the mechanisms and functions are based on 
 work in enterobacteria\, such as Escherichia coli or Salmonella. In contra
 st\, little is known about posttranscriptional regulation in Epsilonproteo
 bacteria\, including the gastric pathogen Helicobacter pylori and the emer
 ging food-borne pathogen Campylobacter jejuni. Helicobacter and Campylobac
 ter lack\, like 50% of all bacteria\, a homolog of the RNA chaperone Hfq\,
  a key player in sRNA-based regulation in enterobacteria. Thus\, we are in
 terested whether they use other auxilliary proteins that replace the funct
 ions of Hfq or whether their sRNAs act independently by novel mechanisms.\
 nOur differential RNA-sequencing approach (dRNA-seq) allowed us to define 
 a genome-wide map of transcriptional start sites (TSS) and revealed >60 sR
 NAs in H. pylori [1]. To understand how transcriptome differences could co
 ntribute to phenotypic differences among strains\, we recently applied a c
 omparative dRNA-seq to multiple C. jejuni strains [2]. Our study revealed 
 that the majority of TSS is conserved among strains\, but we also observed
  strain-specific promoter usage and sRNA repertoires\, which might underli
 e strain-specific gene regulation and phenotypic differences among strains
 . Based on our transcriptome datasets\, we are now using Helicobacter and 
 Campylobacter as new model organisms for riboregulation in bacterial patho
 gens and bacteria without Hfq. We are functionally characterizing abundant
  sRNAs and are especially interested in the roles and underlying molecular
  mechanisms of sRNAs in stress response and virulence control as well as t
 he identification of associated RNA-binding proteins. For example\, we cou
 ld recently show that the highly abundant and conserved sRNA\, RepG\, from
  H. pylori directly base-pairs with a homopolymeric G-repeat in the mRNA l
 eader of the chemotaxis receptor TlpB and that length variation of this G-
 repeat determines the outcome (repression or activation) of RepG-mediated 
 post-transcriptional regulation [3]. We have also identified a first poten
 tial virulence regulating sRNA that directly represses multiple virulence 
 factors. These examples show that identifying and studying sRNAs in bacter
 ia without Hfq can reveal new twists in RNA-mediated regulation and will p
 rovide new insight into mechanisms of gene regulation and virulence contro
 l of bacterial pathogens.\nReferences:\n[1] Sharma\, C.M.\, Hoffmann\, S.\
 , Darfeuille\, F.\, Reignier\, J.\, Findeiss\, S.\, Sittka\, A.\, Chabas\,
  S.\, Reiche\, K.\, Hackermüller\, J.\, Reinhardt\, R. Stadler\,P. F.\, V
 ogel\, J. (2010) The primary transcriptome of the major human pathogen Hel
 icobacter pylori. Nature\, 464\, 250-255\n[2] Dugar G\, Herbig  A\, Förs
 tner KU\, Heidrich N\, Reinhardt R\, Nieselt K\, Sharma CM (2013) High-res
 olution transcriptome maps reveal strain-specific regulatory features of m
 ultiple Campylobacter jejuni isolates. PLoS Genetics 9(5):e1003495\n[3] Pe
 rnitzsch SR\, Tirier S\, Beier D\, Sharma CM  (2014) A variable homopolym
 eric G-repeat defines small RNA-mediated post-transcriptional regulation o
 f a chemotaxis receptor in Helicobacter pylori. PNAS 111(4) E501–E510
LOCATION:SV 1717a
STATUS:CONFIRMED
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