Molecular mechanisms of colicin evolution

This review explores features of the origin and evolution of colicins inEscherichia coli. First, the evolutionary relationships of 16 colicin andcolicin-related proteins are inferred from amino acid and DNA sequencecomparisons. These comparisons are employed to detail the evolutionarymechanisms involved in the origin and diversification of colicin clusters.Such mechanisms include movement of colicin plasmids between strains of E.coli and subsequent plasmid cointegration, transposition- andrecombination-mediated transfer of colicin and related sequences, and rapiddiversification of colicin and immunity proteins through the action ofpositive selection. The wealth of information contained in colicin sequencecomparisons makes this an ideal system with which to explore molecularmechanisms of evolutionary change.