Molecular structure and immunity specificity of colicin E6, an evolutionary intermediate between E-group colicins and cloacin DF13.
AUTOR(ES)
Akutsu, A
RESUMO
The primary structure of a 3.1-kilobase E6 or E3 segment carrying colicin and related genes was determined. Plasmid ColE6-CT14 showed striking homology to ColE3-CA38 throughout this segment, including homology to the secondary immunity gene, immE8, downstream of the E6 or E3 immunity gene. The ColE3-CA38 and ColE6-CT14 sequences, however, contained an exceptional hot spot region encoding both the colicin-active domain (RNase region) and the immunity protein, reflecting their different immunity specificities. On the other hand, some chimeric plasmids were constructed through homologous recombination between colicin E3 and cloacin DF13 operons. The resulting plasmids were deduced to produce chimeric colicins with a colicin E3-type N-terminal part, a cloacin DF13-type C-terminal-active domain, and the DF13 immunity protein. The killing spectra of the chimeric colicins and the immunities of the plasmids were identical to those of colicin E6 and ColE6-CT14, respectively, showing that the colicin E6 immunity specificity is completely equivalent to that of cloacin DF13. Nevertheless, colicin E6 has been found to show a sequence diversity from cloacin DF13 almost to the same extent as that from colicin E3 in their RNase and immunity regions, indicating that only a small number of amino acids defines the immunity specificity for discrimination between colicins E3 and E6 (or cloacin DF13).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=210531Documentos Relacionados
- Molecular structure of the immunity gene and immunity protein of the bacteriocinogenic plasmid Clo DF13.
- Protein H encoded by plasmid CloDF13 is involved in excretion of cloacin DF13.
- Molecular structure and function of the bacteriocin gene and bacteriocin protein of plasmid Clo DF13.
- Clo DF13 plasmid deoxyribonucleic acid-directed in vitro synthesis of biologically active cloacin DF13 and clo DF13 immunity protein.
- Uptake of cloacin DF13 by susceptible cells: removal of immunity protein and fragmentation of cloacin molecules.