Evolutionary expansion of a regulatory network by counter-silencing.
Nat Commun
; 5: 5270, 2014 Oct 28.
Article
in En
| MEDLINE
| ID: mdl-25348042
ABSTRACT
Horizontal gene transfer plays a major role in bacterial evolution. Successful acquisition of new genes requires their incorporation into existing regulatory networks. This study compares the regulation of conserved genes in the PhoPQ regulon of Salmonella enterica serovar Typhimurium with that of PhoPQ-regulated horizontally acquired genes, which are silenced by the histone-like protein H-NS. We demonstrate that PhoP upregulates conserved and horizontally acquired genes by distinct mechanisms. Conserved genes are regulated by classical PhoP-mediated activation and are invariant in promoter architecture, whereas horizontally acquired genes exhibit variable promoter architecture and are regulated by PhoP-mediated counter-silencing. Biochemical analyses show that a horizontally acquired promoter adopts different structures in the silenced and counter-silenced states, implicating the remodelling of the H-NS nucleoprotein filament and the subsequent restoration of open-complex formation as the central mechanism of counter-silencing. Our results indicate that counter-silencing is favoured in the regulatory integration of newly acquired genes because it is able to accommodate multiple promoter architectures.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Salmonella typhimurium
/
Gene Silencing
/
Biological Evolution
/
Gene Regulatory Networks
Language:
En
Journal:
Nat Commun
Journal subject:
BIOLOGIA
/
CIENCIA
Year:
2014
Document type:
Article
Affiliation country:
United States