Plasmid genes increase membrane permeability in Escherichia coli.
The membrane permeability to o-nitrophenyl beta-D-galactoside is increased in the presence of rifampicin in Escherichia coli cells carrying srnB+ or pnd+ plasmids, but not in the cells carrying srnB- or pnd- mutant plasmids. The same permeability alteration was also observed at 42 degrees C when a rpoC4- mutant strain was used as a host strain in the absence of rifampicin. These results and the blockage of the effects by action of chloramphenicol suggest that the increase of permeability to o-nitrophenyl galactoside was caused by the expression of srnB+ or pnd+ gene, respectively. srnB+ gene expression leads to massive RNA degradation, probably through the activation of the rna+ gene product. In an rna- strain carrying the srnB+ plasmid, the extent of RNA degradation was reduced, whereas the permeability to o-nitrophenyl galactoside was increased to the same level as in the rna+ strain. Also, the increase in permeability to o-nitrophenyl galactoside was observed at 30 degrees C, although high-temperature incubation (42 degrees C) was necessary for the induction of RNA degradation. These results suggest that the alteration in permeability is a more direct effect of the expression of srnB+ or pnd+ gene and that the RNA degradation is a secondary phenomenon caused by the alteration in the membrane.
D001426:Bacterial Proteins / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002701:Chloramphenicol / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins / Q000378:metabolism; D009004:Monosaccharide Transport Proteins; D009598:Nitrophenylgalactosides / Q000378:metabolism; D010957:Plasmids; D012329:RNA, Bacterial / Q000378:metabolism; D027981:Symporters; D013696:Temperature; D013862:Thiogalactosides / Q000494:pharmacology
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C050221:LacY protein, E coli; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D012329:RNA, Bacterial; D027981:Symporters; D013862:Thiogalactosides; D009598:Nitrophenylgalactosides; D002701:Chloramphenicol; C031803:thiodigalactoside; C021499:lactose permease