title: Structural and functional properties of colicin M.
abstract: Colicin M of Escherichia coli Cl139 was isolated in pure form. It consisted of a single polypeptide with a molecular weight of 27,000 +/- 2,000. Colicin M lysed sensitive cells of E. coli but had to act continuously up to the point when lysis commenced (after 20 min). Colicin M was largely resistant to hydrolysis by trypsin except when adsorbed to cells. Within 4 to 5 min after addition of colicin M, cells could be rescued by trypsin or sodium dodecyl sulfate. Later, colicin M was apparently inaccessible to these inactivating agents. Killing of cells by colicin M required Ca2+ ions. Cells could be rescued with ethylene glycol-bis(beta-aminoethyl ether)-N,N'-tetraacetate (EGTA) immediately before the onset of lysis. Under these conditions, colicin M remained bound to the cells, and it became again sensitive to trypsin. We conclude that under the influence of EGTA colicin M is removed from its site of action and becomes again accessible to trypsin at the cell surface.
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D002845:Chromatography; D003087:Colicins / Q000302:isolation & purification* / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D008937:Mitomycins / Q000494:pharmacology; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology
chemical_list: D003087:Colicins; D008937:Mitomycins; D012967:Sodium Dodecyl Sulfate; D002122:Calcium Chloride