Surprisingly , the SsrB response regulator positively regulated the formation of biofilms by activating csgD expression in the absence of any phos-pho-donors .
Unphosphorylated SsrB activates csgD expression Biofilm formation in Salmonella Typhimurium is governed by the master regulator , CsgD .
Unphosphorylated SsrB activates csgD expression Biofilm formation in Escherichia coli is governed by the master regulator , CsgD .
An obvious null hypothesis was therefore to test whether SsrB -LRB- in its unphosphorylated state -RRB- , activated the expression of csgD .
We show that under biofilm-inducing conditions , unphosphorylated SsrB is sufficient to activate the expression of csgD .