OmpR phosphorylation regulates ompS1 expression by differentially controlling the use of promoters.
The Salmonella enterica ompS1 gene encodes a quiescent porin that belongs to the OmpC/OmpF family. In the present work we analysed the regulatory effects of OmpR phosphorylation on ompS1 expression. We found that in vivo, OmpR in its phosphorylated form (OmpR-P) was important in the regulation of the two ompS1 promoters: OmpR-P activated the P1 promoter and repressed the P2 promoter in an EnvZ-dependent manner; expression occurs from the P2 promoter in an ompR mutant. In vitro, OmpR-P had a higher DNA-binding-affinity to the ompS1 promoter region than OmpR and OmpRD55A, showing an affinity even higher than that of equivalent DNA regions in the 5'-upstream regulatory sequence of the major porin-encoding genes ompC and ompF. By analysing different environmental conditions, we found that glucose and glycerol enhanced ompS1 expression in the wild-type strain. Interestingly the stimulation by glycerol was OmpR-dependent while the effect of glucose was still observed in the absence of OmpR. Acetyl phosphate produced by the AckA-Pta pathway did not influence ompS1 regulation. These data indicate the important role of the phosphorylation in the activity of OmpR on the differential regulation of both ompS1 promoters and its impact on the pathogenesis.
Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco A. C., Normalistas 800, Colinas de la Normal, Guadalajara 44270, Jalisco, Mexico.
Mario Alberto
MA
Flores-Valdez
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico.
Marcos
M
Fernández-Mora
Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico.
Miguel Ángel
MÁ
Ares
Department of Molecular Genetics and Microbiology, Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.
Jorge A
JA
Girón
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico.
Edmundo
E
Calva
Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico.|Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos 62210, Mexico.
Miguel Ángel
MÁ
De la Cruz
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis*; D015870:Gene Expression / Q000187:drug effects; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D010766:Phosphorylation; D018272:Porins / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012485:Salmonella typhi / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; C094202:OmpS1 protein, Salmonella typhi; D018272:Porins; D014157:Transcription Factors; D005947:Glucose; D005990:Glycerol