Treatment of Escherichia coli K12 C600 with colicin K or E1, but not E3, caused changes in the protein composition of the bacterial cytoplasmic membrane and an impairment of the membrane-associated ATP-linked transhydrogenase activity. The major compositional changes were loss and/or reduction in the levels of protein bands 4, 8, 9, 10, 13, and 18 with approximate molecular weights of 122,000, ...

The colicin typing method for differentiating epidemic strains of Shigella sonnei was evaluated. Forty percent of the strains were untypable, but the method divides 60% of the strains into 15 established colicin types. The method has reasonably good reproducibility, but should not be interpreted with the same degree of confidence as some other characteristics such as serotypes. For this reason,...

Cell walls of E. coli strains B and Cullen contain specific receptors for colicin K and for the T2, T6, and C16 phages. The receptors for the bacteriocin and the T6 virus are located in the outer layers of the cell wall of these microorganisms and are absent in their cytoplasmic membrane. The receptors for colicin K, phage T2, and the T6 and C16 viruses differ in their stability toward enzymes ...

Phleomycin stimulates the degradation of DNA by energy-dependent endonuclease and exonuclease reactions in Escherichia coli rec(+) cells and in recB(-) and recC(-) cells that lack an adenosine triphosphate-dependent nuclease functioning in the repair of ultraviolet (UV) lesions. Exonuclease activity is blocked in T4 phage-infected cells. The endonuclease reaction produces 10(7)-dalton segments ...

ColE9 is a plasmid-encoded protein antibiotic produced by Escherichia coli and closely related species that kills E. coli cells expressing the BtuB receptor. The 15-kDa cytotoxic DNase domain of colicin E9 preferentially nicks double-stranded DNA at thymine bases and shares a common active-site structural motif with a variety of other nucleases, including the H-N-H homing endonucleases and the ...

Channel-forming colicins are bacterial toxins that spontaneously insert into the inner cell membrane of sensitive bacteria to form voltage-gated ion channels. It has been shown that the channel current and the conformational flexibility of colicin E1 channel domain depend on the membrane surface potential, which is regulated by the anionic lipid content and the ion concentration. To better unde...

Bacteriocins related to colicin M, acting via cleavage of the cell wall precursor lipid II, have been characterized in γ- and β-proteobacteria. Depending on the species, immunity is provided by either an inner membrane-anchored periplasmic protein or by an integral membrane protein. In Pseudomonas however, the immunity partner of colicin M-like bacteriocins remains unknown. Based on an in silic...