Figure 7
Two activation modes for PrkC. Two activation modes are proposed for PrkC depending on the physiological state of the bacteria. On the top panel (in blue), we designed the model of activation during stationary phase growth or germination of B. subtilis spores. During stationary phase or before germination, PrkC is distributed all over the cell wall of the bacteria or in the internal membrane of the spore. The binding of muropeptides (germination signal for spores) stimulates PrkC dimerization and autophosphorylation. The activated PrkC can then phosphorylate its cytoplasmic substrates. On the panel below (in red), we designed the model of PrkC activation during bacterial growth. Thanks to interactions with membrane proteins at the poles and at the septum, like hydrolases or proteins of the divisome schematically represented by the white shadow, PrkC molecules get closer to each other. PrkC interacts also with the division protein GpsB which stimulates its autophosphorylation and its kinase activity. The activated PrkC is then able to phosphorylate its cytoplasmic substrates. The feedback loop regulation of PrkC activity by phosphorylated GpsB protein20 is not described here. The divisome schematically represented by the white shadow includes the proteins described in37 and containing EzrA, PBP1, PBP2b, ZapA, SepF, FtsZ, FtsA, FtsL, FtsW, DivIB, DivIC, and DivIVA.
