title: Exclusive localization of colicin A in cell cytoplasm of producing bacteria.
abstract: The production of colicin A in Citrobacter freundii and in Escherichia coli was studied. After induction with low concentrations of mitomycin C, these organisms differed with regards to cell growth, cell viability, and kinetics of colicin A biosynthesis. Despite these differences, immunoferritin labelling on ultra-thin sections of induced frozen cells demonstrated that colicin A was located exclusively within the cell cytoplasm in both types of bacteria. By using protein markers, it was shown that at no time after induction was colicin A accumulated in the periplasmic space or in inner or outer membranes. These results were confirmed by a biochemical approach. For at least 3 h after induction, colicin A remained associated with producing cells and no colicin A activity was found in the periplasmic space. These results are discussed with reference to the synthesis and export of other bacteriocins.
mesh_terms: D002954:Citrobacter / Q000378:metabolism* / Q000648:ultrastructure; D003087:Colicins / Q000096:biosynthesis*; D003593:Cytoplasm / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D008937:Mitomycins / Q000494:pharmacology
chemical_list: D003087:Colicins; D008937:Mitomycins