Documenti full-text disponibili:
Abstract
Diabetes mellitus is considered a risk factor for Group B Streptococcus (GBS) infections. Typically, this pathology is associated to high glucose levels in the bloodstream. Although clinical evidences support this notion, the physiological mechanisms underlying GBS adaptation to such conditions are not yet defined. In the attempt to address this issue, we performed comparative global gene expression analysis of GBS grown under glucose-stress conditions and observed that a number of metabolic and virulence genes was differentially regulated. Of importance, we also demonstrated that by knocking-out the csrRS locus the transcription profile of GBS grown in high-glucose conditions was profoundly affected, with more than a third of glucose-dependent genes, including the virulence factor bibA, found to be controlled by this two-component system. Furthermore, in vitro molecular analysis showed that CsrR specifically binds to the bibA promoter and the phosphorilation increases the affinity of the regulator to this promoter region. Moreover, we demonstrated that CsrR acts as a repressor of bibA expression by binding to its promoter in vivo. In conclusion, this work by elucidating both the response of GBS to pathological glucose conditions and the underlined molecular mechanisms will set the basis for a better understanding of GBS pathogenesis.
Abstract
Diabetes mellitus is considered a risk factor for Group B Streptococcus (GBS) infections. Typically, this pathology is associated to high glucose levels in the bloodstream. Although clinical evidences support this notion, the physiological mechanisms underlying GBS adaptation to such conditions are not yet defined. In the attempt to address this issue, we performed comparative global gene expression analysis of GBS grown under glucose-stress conditions and observed that a number of metabolic and virulence genes was differentially regulated. Of importance, we also demonstrated that by knocking-out the csrRS locus the transcription profile of GBS grown in high-glucose conditions was profoundly affected, with more than a third of glucose-dependent genes, including the virulence factor bibA, found to be controlled by this two-component system. Furthermore, in vitro molecular analysis showed that CsrR specifically binds to the bibA promoter and the phosphorilation increases the affinity of the regulator to this promoter region. Moreover, we demonstrated that CsrR acts as a repressor of bibA expression by binding to its promoter in vivo. In conclusion, this work by elucidating both the response of GBS to pathological glucose conditions and the underlined molecular mechanisms will set the basis for a better understanding of GBS pathogenesis.
Tipologia del documento
Tesi di dottorato
Autore
Di Palo, Benedetta
Supervisore
Dottorato di ricerca
Scuola di dottorato
Scienze biologiche, biomediche e biotecnologiche
Ciclo
24
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
GBS, CsrRS, BibA
URN:NBN
DOI
10.6092/unibo/amsdottorato/4805
Data di discussione
27 Aprile 2012
URI
Altri metadati
Tipologia del documento
Tesi di dottorato
Autore
Di Palo, Benedetta
Supervisore
Dottorato di ricerca
Scuola di dottorato
Scienze biologiche, biomediche e biotecnologiche
Ciclo
24
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
GBS, CsrRS, BibA
URN:NBN
DOI
10.6092/unibo/amsdottorato/4805
Data di discussione
27 Aprile 2012
URI
Statistica sui download
Gestione del documento: