Because the primary mechanism for antibiotic-mediated induction of phage propagation is the SOS response, we also determined the level of recA expression after exposure to bAGPs.
Although use of chlortetracycline and oxytetracycline in cattle is not consistent (4), the levels of SOS response induction and Stx phage propagation by these 2 antibiotics were comparable (Figure 1).
The DNA cleavage event would be expected to induce a cellular SOS response to DNA damage.
mreD cells was associated with induction of the SOS response, as expected if loss of termini resulted from the chromosome cleavage.
Mutant bacteria with no functional SOS response
were more vulnerable to the three classes of antibiotics studied.
In this context, exposure to agents which interfere with DNA replication or which are able to cause DNA damages, induces the expression of a set of genes designed SOS response
LexA is a key regulator of the SOS response
and we will use these new mutants to determine if regulation of the SOS response
, the type III secretion system, and coronatine biosynthesis are linked.
Researchers have shown that the presence of antibiotics activates SOS response
and thus increases concentration of RecA protein.
Figure 3 illustrates a literature-based linkage map between genes in the SOS response
for the repair of DNA damage.
Another effect of the SOS response
, activated by fluoroquinolone-induced damage to the bacterial DNA, is the discontinuation of cell replication.
In what biologists call the SOS response
, the bacterium activates a protein called RecA.
Phage production is linked to induction of the bacterial SOS response
, a ubiquitous response to DNA damage.