The ompB operon partially determines differential expression of OmpC in Salmonella typhi and Escherichia coli
Por:
Martínez-Flores I., Cano R., Bustamante V.H., Calva E., Puente J.L.
Publicada:
1 ene 1999
Resumen:
Expression of the Escherichia coli OmpC and OmpF outer membrane proteins is regulated by the osmolarity of the culture media. In contrast, expression of OmpC in Salmonella typhi is not influenced by osmolarity, while OmpF is regulated as in E. coli. To better understand the lack of osmoregulation of OmpC expression in S. typhi, we compared the expression of the ompC gene in S. typhi and E. coli, using ompC-lacZ fusions and outer membrane protein (OMP) electrophoretic profiles. S. typhi ompC expression levels in S. typhi were similar at low and high osmolarity along the growth curve, whereas osmoregulation of E. coli ompC in E. coli was observed during the exponential phase. Both genes were highly expressed at high and low osmolarity when present in S. typhi, while expression of both was regulated by osmolarity in E. coli. Complementation experiments with either the S. typhi or E. coli ompB operon in an S. typhi ?ompB strain carrying the ompC-lacZ fusions showed that both S. typhi and E. coli ompC were not regulated by osmolarity when they were under the control of S. typhi ompB. Interestingly, in the same strain, both genes were osmoregulated under E. coli ompB. Surprisingly, in E. coli ?ompB, they were both osmoregulated under S. typhi or E. coli ompB. Thus, the lack of osmoregulation of OmpC expression in S. typhi is determined in part by the ompB operon, as well as by other unknown trans-acting elements present in S. typhi.
Filiaciones:
Martínez-Flores I.:
Depto. de Microbiol. Molecular, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Morelos 62250, Mexico
Cano R.:
Depto. de Microbiol. Molecular, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Morelos 62250, Mexico
Bustamante V.H.:
Depto. de Microbiol. Molecular, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Morelos 62250, Mexico
Calva E.:
Depto. de Microbiol. Molecular, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Morelos 62250, Mexico
Instituto de Biotecnología, UNAM, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
Puente J.L.:
Depto. de Microbiol. Molecular, Instituto de Biotecnología, Univ. Nac. Auton. de México, Cuernavaca, Morelos 62250, Mexico
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