Cross talk and Metabolism in Escherichia coli

本项目旨在研究磷酸(Pho)调节子和creabcd(以前称为Phom操纵子)中基因之间相互作用的遗传和分子基础，并确定creabcd操纵子在大肠杆菌中的生物学作用。该项目完全专注于涉及creabcd操纵子的调控相互作用。Pho调节子编码获得环境磷(P)的基因，并在外部(EXT)无机磷(PI)水平限制生长时被诱导。CreABCD操纵子的表达不受PI(Ext)的影响，它似乎对中枢代谢中形成的内部(INT)有机磷水平做出反应，这种水平可能是在底物水平的磷酸化(在糖酵解或TCA循环中)在PI(INT)结合到有机磷的步骤中形成的。在代谢途径中，基因之间存在相互调节作用；PI(Ext)到PI(Int)再到有机磷(Int)，其中PI(Ext)调节pho调节子，而有机磷(Int)可能既调节pho调节子又调节creABCD操纵子。这种串扰可能是对细胞新陈代谢和生长的一般(全局)控制至关重要的潜在控制机制的一个例子；这在细菌的基因表达控制中尤其明显，但很可能在真核细胞中也发挥同样的作用。

This project is to study the genetic and molecular basis of regulatory interactions termed cross talk between the phosphate (PHO) regulon and genes in the creABCD, formerly called phoM, operon and to define the biological role of the creABCD operon in Escherichia coli. The project focuses entirely on regulatory interactions involving the creABCD operon. The PHO regulon encodes genes for the acquisition of environmental phosphorus (P) and is induced when the external (ext) inorganic phosphate (Pi) level is growth limiting. The creABCD operon, whose expression is unaffected by Pi(ext), seems to respond to the level of an internal (int) organophosphate formed in central metabolism, which may be formed in substrate-level phosphorylation (in glycolysis or the TCA cycle) at a step where Pi(int) is incorporated into organophosphate. Regulatory interactions are expected between genes in a metabolic pathway; Pi(ext) to Pi(int) to organophosphate (int) in which Pi(ext) regulates the PHO regulon and organophosphate(int) may regulate both the PHO regulon and the creABCD operon. Such cross talk may be an example of an underlying control mechanisms essential for general (global) control of cell metabolism and growth; this is especially apparent in the control of gene expression in bacteria, but may quite possibly play the same role in eucaryotic cells too.