Open AccessReduced activity of TonB‐dependent functions in strains of Escherichia coli
Author(s) -
Mann Barbara J.,
Holroyd Catherine D.,
Bradbeer Clive,
Kadner Robert J.
Publication year - 1986
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1986.tb01282.x
Subject(s) - colicin , escherichia coli , plasmid , biology , bacterial outer membrane , gene , gene product , bacteria , genetics , microbiology and biotechnology , gene expression
The tonB gene product is necessary for the energy‐dependent transport of ferric chelates and vitamin B 12 across the Escherichia coli outer membrane. When carried on multicopy plasmids, the cloned tonB gene complemented tonB hosts, restoring transport of ferri‐siderophone complexes and vitamin B 12 , and susceptibility to the group B colicins and phage ф80. The levels of these activities were all markedly lower than when the tonB + gene was present in single copy. This depression of TonB function occurred even when the chromosome carried the normal tonB + allele, but plasmids carrying only a portion of the tonB gene, including the 5′‐regulatory region, were not inhibitory.