Our results show that PhoBR is capable of inducing fimZ expression , whereas PhoPQ does upregulate hilE in an FimZ-dependent manner .
the PhoPQ signal leads to induction of hilE expression
Even in the absence of hilE , hilA : : lacZY plasmid reporter levels still showed a 25.9-fold reduction when the PhoPQ regulators were activated by magnesium .
Since our studies indicated that PhoPQ plays a role in inducing hilE expression , we examined whether the phoBR regulon also regulates hilA via HilE .
Under conditions of low magnesium concentration , the PhoPQ regulon is activated , leading to the phosphorylation of FimZ with the subsequent increase in hilE expression .