9405929 Wanner This proposal is to continue studies on "cross regulation" in central metabolic pathways of Escherichia coli. Cross regulation refers to the control of a response regulator of one two-component regulatory system by a different regulatory system. Two such controls act on the phosphate (PHO) regulon. One involves the CreC sensor kinase (which is encoded together with its partner response regulator CreB by catabolite regulatory creABCD operon); the other involves acetyl phosphate. Both of these controls appear to be important, for each provides a way to couple control of the PHO regulon (by the level of extracellular Pi) to pathways of central metabolism for the incorporation of intracellular Pi into ATP (the primary phosphoryl donor in metabolism). Specific aims of this proposal are: (i) to identify genes regulated by the CreB-CreC two- component regulatory system; (ii) to examine acetyl phosphate synthesis in normal and mutant cells; and (iii) to conduct gene regulation studies to assess the importance of cross regulation in cell physiology. %%% Cells undergo numerous adjustments of central pathways of metabolism in response to the carbon and energy sources. These adjustments require a high degree of regulatory interactions between and among different cellular functions in order to permit the cell to grow. Cross regulation provides a means for the coordinate regulation among these different pathways. This study will focus on cross regulation in the control of genes closely related to phosphorus metabolism (an essential nutrient whose assimilation is closely connected to central metabolic pathways.) Although these studies will be carried out entirely in the model bacterium Escherichia coli, the results are likely to pertain to all types of cells. This is because of the unity among central pathways. Two mechanisms of cross regulation will be explored. One involves protein phosphorylation, an important process for the control of regulatory proteins (in all cells). The other involves a small molecule (acetyl phosphate) which appears to act as an effector molecule in the control of (certain) regulatory proteins known to be affected by protein phosphorylation. ***
