Plasmids derived from lambdoid bacteriophages as models for studying replication of mobile genetic elements responsible for the production of Shiga toxins by pathogenic Escherichia coli strains.
BACKGROUND
Genes encoding Shiga toxins in pathogenic Escherichia coli strains (Shiga toxin-producing E. coli, STEC) are located on lambdoid prophages. However, studies on the replication of these phages were not reported to date.


METHODS
Plasmids derived from Shiga toxin-converting phages were constructed, introduced into wild-type E. coli strain and studied using methods of molecular genetics.


RESULTS
The studied replicons behaved similarly to plasmids derived from bacteriophage lambda, and DNA sequence analysis revealed their high level of homology to the lambda replication region. Nevertheless, contrary to lambda and two of six tested plasmids, four tested replicons were able to replicate in the E. colidnaA46 mutant. Specific nucleotide differences, causing amino acid substitutions relative to wild-type lambda O and P proteins, appeared to be responsible for this phenotype.


CONCLUSIONS
We conclude that replicons of phages bearing Shiga toxin genes are functionally similar to that of bacteriophage lambda, however, some of them have important differences which influence replication regulation. Furthermore, our results may suggest that there are newly discovered molecular interactions in the DNA replication regulation of lambda and lambdoid phages. Hence, plasmids derived from lambdoid phages appear to be convenient models to study the replication of Shiga toxin-converting bacteriophages.
Department of Molecular Biology, University of Gdańsk, Gdańsk, Poland.
Bozena
B
Nejman
Joanna M
JM
Loś
Marcin
M
Łoś
Grzegorz
G
Wegrzyn
Alicja
A
Wegrzyn
D001483:Base Sequence; D003090:Coliphages / Q000235:genetics*; D004261:DNA Replication; D020071:Interspersed Repetitive Sequences; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D039002:Prophages / Q000235:genetics*; D022603:Shiga Toxins / Q000235:genetics*; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000502:physiology
D022603:Shiga Toxins