MODE OF ACTION OF A BACTERIAL FUNCTION INVOLVED IN CELL GROWTH CONTROL

我们一直在研究蛋白质降解在调节中的作用

We have been studying the role that protein degradation plays in regulating cell growth control, through the study of the proteases which carry out ATP-dependent proteolysis in E. coli. The Lon protease degrades RcsA, a positive regulator of capsular polysaccharide synthesis, and SulA, a cell division inhibitor. We have demonstrated that RcsA interacts in the cell with another positive regulator, RcsB to promote efficient capsule synthesis. The Clp protease, a second major ATP-dependent protease, contains a large subunit, ClpA, with ATPase activity; this subunit has been well conserved in both other prokaryotic cells and eukaryotic cells. The smaller subunit, ClpP, contains the active site of the protease, and undergoes a self-processing reaction. The small subunit is also conserved in many cells. The structure and general organization of the Clp protease suggests that it has many similarities to the eukaryotic energy-dependent proteases which degrade ubiquitin-conjugated proteins. Alp, a third energy-dependent protease activity, which can substitute for Lon when overproduced, consists of a set of closely linked genes and a positive regulator. In another approach to the study of bacterial cell growth control, mutants which may be defective in partition of the bacterial chromosome have been selected, mapped and characterized.