TY - JOUR
T1 - RpoS integrates CRP, Fis, and PhoP signaling pathways to control Salmonella Typhi hlyE expression
AU - Jofré, Matí R.
AU - Rodríguez, Leonardo
AU - Villagra, Nicolás A.
AU - Hidalgo, Alejandro A.
AU - Mora, Guido C.
AU - Fuentes, Juan A.
N1 - Funding Information:
This work was supported by FONDECYT (Fondo Nacional de Desarrollo Científico y Tecnológico, Government of Chile) Grants 1110120 (GCM) and 11121506 (JAF) and UNAB-Grant DI-13-11/I (MRJ) and DI-222-12/N (JAF); MRJ is a MECESUP fellow program “Fortalecimiento del programa de Doctorado en Biociencias Moleculares” Grant UAB-0802. AAH is a FONDECYT Postdoctoral, fellow Grant 3130523.
PY - 2014/5/31
Y1 - 2014/5/31
N2 - Background: SPI-18 is a pathogenicity island found in some Salmonella enterica serovars, including S. Typhi. SPI-18 harbors two ORFs organized into an operon, hlyE and taiA genes, both implicated in virulence. Regarding the hlyE regulation in S. Typhi, it has been reported that RpoS participates as transcriptional up-regulator under low pH and high osmolarity. In addition, CRP down-regulates hlyE expression during exponential growth. Previously, it has been suggested that there is another factor related to catabolite repression, different from CRP, involved in the down-regulation of hlyE. Moreover, PhoP-dependent hlyE up-regulation has been reported in bacteria cultured simultaneously under low pH and low concentration of Mg2+. Nevertheless, the relative contribution of each environmental signal is not completely clear. In this work we aimed to better understand the regulation of hlyE in S. Typhi and the integration of different environmental signals through global regulators. Results: We found that Fis participates as a CRP-independent glucose-dependent down-regulator of hlyE. Also, Fis and CRP seem to exert the repression over hlyE through down-regulating rpoS. Moreover, PhoP up-regulates hlyE expression via rpoS under low pH and low Mg2+ conditions. Conclusions: All these results together show that, at least under the tested conditions, RpoS is the central regulator in the hlyE regulatory network, integrating multiple environmental signals and global regulators.
AB - Background: SPI-18 is a pathogenicity island found in some Salmonella enterica serovars, including S. Typhi. SPI-18 harbors two ORFs organized into an operon, hlyE and taiA genes, both implicated in virulence. Regarding the hlyE regulation in S. Typhi, it has been reported that RpoS participates as transcriptional up-regulator under low pH and high osmolarity. In addition, CRP down-regulates hlyE expression during exponential growth. Previously, it has been suggested that there is another factor related to catabolite repression, different from CRP, involved in the down-regulation of hlyE. Moreover, PhoP-dependent hlyE up-regulation has been reported in bacteria cultured simultaneously under low pH and low concentration of Mg2+. Nevertheless, the relative contribution of each environmental signal is not completely clear. In this work we aimed to better understand the regulation of hlyE in S. Typhi and the integration of different environmental signals through global regulators. Results: We found that Fis participates as a CRP-independent glucose-dependent down-regulator of hlyE. Also, Fis and CRP seem to exert the repression over hlyE through down-regulating rpoS. Moreover, PhoP up-regulates hlyE expression via rpoS under low pH and low Mg2+ conditions. Conclusions: All these results together show that, at least under the tested conditions, RpoS is the central regulator in the hlyE regulatory network, integrating multiple environmental signals and global regulators.
KW - Catabolite repression
KW - Fis protein
KW - cAMP-receptor protein
KW - hlyE
KW - phoP
KW - rpoS
UR - http://www.scopus.com/inward/record.url?scp=84923858846&partnerID=8YFLogxK
U2 - 10.1186/1471-2180-14-139
DO - 10.1186/1471-2180-14-139
M3 - Article
C2 - 24885225
AN - SCOPUS:84923858846
SN - 1471-2180
VL - 14
JO - BMC Microbiology
JF - BMC Microbiology
IS - 1
M1 - 139
ER -