Exploring the Structure and Dynamics of Ceramide Channels

智力上的优点。膜将细胞内部隔开，并将每个细胞与其环境分开。一般的信条是，蛋白质形成了特定分子通过这些膜转移的运输途径。然而，一种自然产生的类脂，神经酰胺，也被证明能够形成能够跨膜转移蛋白质的大通道。这与神经酰胺启动一种称为细胞凋亡的程序性细胞死亡的能力不谋而合。这个过程中的一个关键步骤是从线粒体释放蛋白质，很可能是通过神经酰胺通道。已知的调节蛋白质释放的蛋白质(Bcl2家族的成员)也调节神经酰胺通道。这项拟议的研究是为了了解蛋白质如何控制神经酰胺通道。由于许多证据表明神经酰胺通道是刚性结构，通过氢键高度交联，一个可行的假设是蛋白质与通道结合，导致结构变化，通过整个结构涟漪形成通道。这一假说和其他假说将用动力学和热力学方法以及微流体学进行检验。此外，将通过蛋白质突变和使用神经酰胺的化学类似物来探索蛋白质和神经酰胺通道之间的相互作用。这些互补性实验将深入了解蛋白质对脂质宏观结构的新调节，并将细胞生物学功能的生物物理和机制理解联系起来。这项研究还将增加我们对细胞凋亡这一极其重要的过程的理解。广泛的影响：这项工作已经并将继续涉及到对高中、本科生、研究生和博士后水平的培训。通常情况下，来自当地高中的五到七名本科生(主修工程、化学或生物)和一名暑期学生将与首席调查员密切合作。这项研究也对调查员的教学产生了很大的影响。他越来越多地认识到理解生物学基本物理学的重要性，这促使他倡导对生命科学专业本科生的物理教学进行根本性改革。作为一项试验计划，国际和平研究所将继续教授一门名为《生命系统物理学》的荣誉课程，作为新物理课程的一部分，该课程将在项目期间扩大。

Intellectual merit. Membranes compartmentalize the cell interior and separate each cell from its environment. The general dogma is that proteins form the transport pathways by which specific molecules are translocated across these membranes. However, a naturally-occurring lipid, ceramide, has also been shown to form large channels capable of translocating proteins across membranes. This coincides with ability of ceramide to initiate a form of programmed cell death called apoptosis. A key step in this process is the release of proteins from mitochondria, likely through ceramide channels. Proteins known to regulate the protein release (members of the Bcl-2 family) also regulate ceramide channels. The proposed research is to understand how proteins control ceramide channels. Since much evidence suggests that ceramide channels are rigid structures, highly cross-linked by hydrogen bonding, a working hypothesis is that proteins bind to the channel causing a structural change that ripples through the entire structure to form the channel. This and other hypotheses will be tested using both kinetic and thermodynamics approaches and microfluidics. In addition, the interactions between the proteins and ceramide channels will be probed by mutations in the protein and the use of chemical analogs of ceramide. These complementary experiments will yield insights into the novel regulation of lipid macrostructures by proteins and will link biophysical and mechanistic understanding of cell biological function. This research will also add to our understanding of the extremely important cellular process of apoptosis.Broader impacts: The work has and will continue to involve the training of students at the high school, undergraduate, graduate, and post-doctoral levels. Typically five to seven undergraduates (majoring in engineering, chemistry or biology) and one summer student from a local high school will work closely with the principal investigator. The research has also greatly influenced the teaching of the investigator. His growing recognition of the importance of understanding the underlying physics of biology has led him to advocate for a radical change in the teaching of physics to undergraduate life science majors. As a pilot project, the PI will continue to teach an honors course entitled 'Physics of Living Systems' as part of a new physics curriculum, which will be expanded during the project period.