Figure 2

The models of the R. sphaeroides chemotaxis system. The different connecitvities modelled for CheY₃ and CheY₄ are shown in this diagram. The coloured lines represent three models presented in this paper. In the blue model CheY₃-P and CheY₄-P bind to FliM in the motor co-operatively with CheY₆-P. In the red model CheY₃ and CheY₄ form a connection with the cytoplasmic cluster and act antagonistically to ligand in altering the kinase activity of CheA₄; therefore, the increase in CheY_3/4-P acts to increase the rate of CheA₃ phosphorlyation by CheA₄. In the magenta model CheY_3/4 interact with CheA₃ preventing CheY₆ binding and hence phosphotransfer. The fourth model corresponds to a model, in which CheY₃ and CheY₄ act as phosphate sinks only and hence do not interact with anything. This is referred to as the grey model in this paper. It should be noted that the other three models also contain this interconnection and that the difference in the grey model is that only this connection exists.