FIGURE 1.
Working model for the BceRS-BceAB bacitracin resistance system of B. subtilis. Bacitracin is bound directly by the transporter BceAB. BceAB and BceS interact to form a sensory complex in the membrane. ATP hydrolysis by the transporter triggers the activation of BceS, which in turn leads to phosphorylation of BceR. Activation of the target promoter (PbceA) by BceR then induces increased production of BceAB to ensure resistance. Interactions between proteins are marked by double-headed arrows; events relating to transcription are labeled with dotted arrows; the potential interaction of BceR with the sensory complex of BceS and BceAB is indicated with a question mark.