Osmoregulatory expression of porin genes in Escherichia coli: a comparative study on strains B and K-12.
Escherichia coli K-12 produces both the OmpF and OmpC porins, the relative amounts of which in the outer membrane are affected in a reciprocal manner by the osmolarity of the growth medium. In contrast, E. coli B produces only the OmpF porin, regardless of the medium osmolarity. In this study, it was revealed that there is an extensive deletion within the ompC locus of the E. coli B chromosome. Cloning and nucleotide sequencing of the regulatory gene, ompR, of E. coli B revealed that there are two amino acid alterations (Lys-6 to Asn and Ala-130 to Thr) in the amino acid sequence of the OmpR protein, as compared with that of E. coli K-12. It is suggested that these particular amino acid alterations are responsible for the constitutive expression of the ompF gene observed in E. coli B.
Mizuno
T
T
Laboratory of Microbiology, School of Agriculture, Nagoya University, Japan.
Shinkai
A
A
Matsui
K
K
Mizushima
S
S
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D018272:Porins; D015183:Restriction Mapping; D014882:Water-Electrolyte Balance
D001425:Bacterial Outer Membrane Proteins; D018272:Porins