Genetics and Physiology of Colicin-Tolerant Mutants of Escherichia coli
Discovered in the 1920s by Andre Gratia, colicins are water-soluble proteins that when produced by certain proteins, can kill
similar kinds of bacteria. Initially believed to be promising anti-bacterial agents, colicins soon proved to be poorly suited
for the task and for decades were largely ignored by researchers. In 1963, Masayasu Nomura demonstrated that colicins are
able to kill bacteria by damaging the membrane of the bacterial cell. As a result of Nomura's work, Luria turned his focus
to colicins. While on leave at the Institut Pasteur in Paris in 1963, Luria found that one particular colicin, E1, made bacterial
cells incapable of accumulating the substances they required to maintain the cell by effectively blocking the function of
transport of proteins through the membrane. After he returned to MIT, the colicin work became the focus of his laboratory.
Here, in one of his earliest published articles on the subject, Luria found that a series of colicin-tolerant mutants of a
strain of E. coli, which adsorbed colicins but were not killed by them, were isolated and studied genetically and physiologically.
He found three major classes of mutants, which he termed tol II (tolerant to colicins A, E1, E2, E3, and K), tol III (tolerant
to A, E2, E3, and K), and tol VIII (tolerant to E1 only). He noted that these mutants were extremely sensitive to deoxycholate
and to methylene blue, acridines, and several other compounds. Luria attributed this sensitivity to increased uptake due to
selective alteration of the permeability barrier.
Item is a photocopy.
Number of Image Pages:
12 (1,494,839 Bytes)
1967-10 (October 1967)
Nagel de Zwaig, Rosa
Luria, Salvador E.
Periodical: Nagel de Zwaig, Rosa, and Salvador E. Luria. "Genetics and Physiology of Colicin-Tolerant Mutants of Escherichia coli."
Journal of Bacteriology 94, 4 (October 1967): 1112-1123. Article. 12 Images.
American Society for Microbiology
Reproduced with permission of the American Society for Microbiology.
Reproduced with permission of the American Philosophical Society.