title: Heterologous expression of Escherichia coli porin genes in Salmonella typhi Ty2: regulation by medium osmolarity, temperature and oxygen availability.
abstract: Electrophoretic analysis of outer membrane proteins showed that Salmonella typhi OmpC expression is not reciprocally regulated relative to OmpF as described for Escherichia coli and S. typhimurium. When bacteria were grown in minimal media, both OmpC and OmpF were repressed as the osmolarity increased. However, in Luria broth, expression of OmpC was slightly induced by osmolarity up to 0.3 osmM. Plasmids bearing E. coli ompC-lacZ or ompF-lacZ gene fusions were studied for their expression in S. typhi and E. coli. Under anaerobic growth conditions, expression of ompC-lacZ in S. typhi was maximal at 0.16 osmM, while in E. coli expression was maximal at 0.7 osmM. ompF-lacZ expression was similarly repressed by medium osmolarity and anaerobiosis in both species. In contrast, a drastic difference in the regulation of OmpF by temperature was observed; at 37 degrees C ompF-lacZ expression was repressed in E. coli, while in S. typhi it was induced.
authors.affiliation: Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: I
authors.initials: I
authors.lastname: Contreras
authors.forename: L
authors.initials: L
authors.lastname: Muñoz
authors.forename: C S
authors.initials: CS
authors.lastname: Toro
authors.forename: G C
authors.initials: GC
authors.lastname: Mora
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D009994:Osmolar Concentration; D010100:Oxygen / Q000378:metabolism; D018272:Porins / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics; D012485:Salmonella typhi / Q000235:genetics*; D013696:Temperature
chemical_list: D001425:Bacterial Outer Membrane Proteins; D018272:Porins; D011994:Recombinant Proteins; D010100:Oxygen