Helicobacter pylori is a major human pathogen responsible for many severe gastric diseases. The most virulent strains contain a 40-Kb cag pathogenicity island (cag-PAI) that encodes a type-IV secretion system able to translocate in the host cell the cag-encoded toxin CagA, peptidoglycan fragments and possibly other factors not yet identified. These virulence factors are responsible for the pathogenic phenotype in the host, such as induction and secretion of proinflammatory cytokines, cell elongation and motily. The function of genes encoded by the cag-PAI and their regulation are currently subject of investigation. Systematic promoter mapping and transcriptional analyses of the cag-PAI showed high level expression of a putative noncoding cag-sRNA corresponding to the 5’UTR of the non-essential HP0536 gene. , conserved in all cag-positive H. pylori strains. The promoter of this cag-sRNA contains a typical sigma80 (RpoD) TATAAT box and lacks sequences with similarity to known regulator consensus motifs . Nevertheless, we found out that the heat-shock and stress regulator HspR positively regulates the expression of the cag-sRNA, likely in an indirect way, as footprinting assay with purified HspR protein could not detect a direct binding in vitro. To establish the role of the cag-sRNA we generated a knock-out mutant and demonstrated through microarray and primer extension approaches that the loss of the cag-sRNA gene doesn’t affect the transcript levels of any of the cag-PAI genes. However, we observed that in the cag-sRNA mutant there is a transcriptional upregulation of many sigma54 (rpoN)-dependent operons (FlaB, FlgB, FlgDE’, FlgE, FlgK, etc), hinting at the involvement of the cag-sRNA in the motility and chemotaxis pathways. To discover functional target of the cag-sRNA we performed bioinformatic analyses within the regulatory network of motility and chemotaxis genes. The putative targets we have identified are under validation.

Study of a putative small non-coding RNA (sRNA) in the Helicobacter pylori cag pathogenicity island

VANNINI, ANDREA;DANIELLI, ALBERTO;SCARLATO, VINCENZO
2011

Abstract

Helicobacter pylori is a major human pathogen responsible for many severe gastric diseases. The most virulent strains contain a 40-Kb cag pathogenicity island (cag-PAI) that encodes a type-IV secretion system able to translocate in the host cell the cag-encoded toxin CagA, peptidoglycan fragments and possibly other factors not yet identified. These virulence factors are responsible for the pathogenic phenotype in the host, such as induction and secretion of proinflammatory cytokines, cell elongation and motily. The function of genes encoded by the cag-PAI and their regulation are currently subject of investigation. Systematic promoter mapping and transcriptional analyses of the cag-PAI showed high level expression of a putative noncoding cag-sRNA corresponding to the 5’UTR of the non-essential HP0536 gene. , conserved in all cag-positive H. pylori strains. The promoter of this cag-sRNA contains a typical sigma80 (RpoD) TATAAT box and lacks sequences with similarity to known regulator consensus motifs . Nevertheless, we found out that the heat-shock and stress regulator HspR positively regulates the expression of the cag-sRNA, likely in an indirect way, as footprinting assay with purified HspR protein could not detect a direct binding in vitro. To establish the role of the cag-sRNA we generated a knock-out mutant and demonstrated through microarray and primer extension approaches that the loss of the cag-sRNA gene doesn’t affect the transcript levels of any of the cag-PAI genes. However, we observed that in the cag-sRNA mutant there is a transcriptional upregulation of many sigma54 (rpoN)-dependent operons (FlaB, FlgB, FlgDE’, FlgE, FlgK, etc), hinting at the involvement of the cag-sRNA in the motility and chemotaxis pathways. To discover functional target of the cag-sRNA we performed bioinformatic analyses within the regulatory network of motility and chemotaxis genes. The putative targets we have identified are under validation.
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A. Vannini; A. Danielli; V. Scarlato
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/106066
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