Cell-cell signaling through regulated proteolysis

描述（由申请人提供）：信号通过膜传导的能力是一种基本的生物现象，目前对其了解甚少。最近，一种新的跨膜转导机制被描述。在该模型中，嵌入膜内的蛋白酶被触发以催化膜锚定转录因子的蛋白水解释放。这些新型蛋白酶是多聚膜蛋白，催化位点嵌入脂质双分子层。为了更深入地了解信息是如何通过这些膜嵌入蛋白酶转导的，我们正在研究一种信号转导途径，该途径导致枯草芽孢杆菌中参与孢子形成的转录因子的蛋白水解激活。这种生物体易于进行遗传和生化分析，使其成为研究这类重要蛋白酶的理想系统。

DESCRIPTION (provided by applicant): The ability to transduce a signal across a membrane is a basic biological phenomenon that remains only poorly understood. Recently, a new mechanism of transduction across a membrane has been described. In this model proteases embedded within the membrane are triggered to catalyze the proteolytic release of membrane-anchored transcription factors. These novel proteases are polytopic membrane proteins with catalytic sites embedded in the lipid bilayer. To gain a deeper understanding into how information is transduced by these membrane-embedded proteases we are studying a signal transduction pathway that results in the proteolytic activation of a transcription factor involved in spore formation in the bacterium Bacillus subtilis. The ease with which genetic and biochemical analysis can be carried out in this organism makes this an ideal system to study this important class of proteases. The developmentally regulated transcription factor (sigmaK) is proteolytically released from the membrane by a membrane-embedded metalloprotease known as SpolVFB (referred to as B). B is activated by a signaling protease (IVB) located on the other side of the membrane. The specific hypothesis underlying the proposed research is that cell-cell signaling during sporulation is achieved by the action of IVB on one side of the membrane, which triggers the activity of the membrane-embedded metalloprotease B on the opposite side. We further hypothesize that additional regulatory proteins modulate this two-step proteolytic cleavage pathway, which results in transcription factor activation. Specifically, we propose to: 1. Determine how the IVB signaling molecule triggers B protease activity; 2. Characterize three regulators that modulate the timing of sigmaK activation; 3. Reconstitute and characterize B-mediated pro-sigmaK processing in vitro.