Iron uptake in colicin B-resistant mutants of Escherichia coli K-12

Publisher Website
Google Scholar
Abstract
Four classes of colicin B-resistant mutants of E. coli K-12 were examined for defects in Fe uptake. All 4 mutant classes (cbt, exbC, exbB and tonB) were defective in the uptake of ferri-enterochelin. The tonB mutant was also defective in citrate-, ferrichrome- and rhodoturulic acid-mediated Fe uptake. The defects in Fe transport were reflected in increased sensitivity to Fe chelators and to Cr and Al salts, and in hypersecretion of enterochelin. One of the mutants (cbt) was apparently defective in outer membrane ferri-enterochelin receptor activity. aroE derivatives (unable to synthesize enterochelin) of the 4 mutant classes and the parent strain produced increased amounts of 2 outer membrane polypeptides when grown under Fe stress. These polypeptides are implicated in ferri-enterochelin receptor activity.