Colicins are bacteriocins produced by Escherichia coli.
Colicin E8-J is a complex of proteins A and B, with protein A exhibiting DNase activity inhibited by protein B.
This activity is similar to colicin E2.
Purpose of the Study:
To characterize the activities and gene structures of Colicin E8-J and its immunity protein.
To elucidate the evolutionary relationships of Colicin E8-J within the E-group of Col plasmids.
Main Methods:
DNA sequencing of the downstream half of the Colicin E8-J colicin operon.
Sequence homology analysis comparing Colicin E8-J with other E-group colicins (ColE2-P9 and ColE3-CA38).
Main Results:
The nucleotide sequence of Colicin E8-J showed high homology to Colicin E2-P9, with variations in the 3'-terminal segment of the colicin and immunity genes.
The immE8 gene of Colicin E8-J was extensively homologous to the immE2-like gene of Colicin E3-CA38.
These findings suggest Colicin E8-J is evolutionarily situated between ColE2-P9 and ColE3-CA38.
Conclusions:
Colicin E8-J shares functional and structural similarities with other E-group colicins.
Sequence analysis provides insights into the evolution of E-group Col plasmids.
The study clarifies the evolutionary position of Colicin E8-J among related bacteriocins.