Conformational transitions of membrane-spanning peptides

膜跨越肽的构象转变******膜蛋白嵌入所有活细胞的膜中，是连接内外世界的分子纽带。在过去的十年中，这些蛋白质占所有人类基因的20-30%，占FDA批准的药物靶点的70%，它们调节生物脂质双分子层的分子交通和信息流。鉴于膜蛋白的关键突变是许多人类疾病的根本原因，了解和控制其结构的努力在基础和应用研究中具有很大的兴趣。******膜蛋白的突变可以被视为生物物理事件，它不仅影响对功能至关重要的跨膜螺旋的包装和静电相互作用，还影响给定蛋白质片段与细胞脂质双分子层环境的相容性。因此，我们的研究集中在构成膜蛋白基本成分的蛋白质片段上。在nserc资助的研究中，目前的应用是一种更新，我们已经推进了分子设计、化学合成、生化和生物物理方法的使用，以揭示“给定序列如何被细胞选择用于膜插入，接收脂质环境如何作用以稳定插入的片段，以及最终单个氨基酸的变化如何彻底改变蛋白质的生物学命运”的代码。在此基础上，我们提出设计和化学合成几个系列组成相同的肽，以产生相同组成的序列，但疏水和极性残基的位置和平衡不同。我们将通过凝胶电泳和圆二色光谱等生化技术评估肽-脂质的相互作用。同时，我们将与世界膜蛋白结构专家Gunnar von Heijne教授（斯德哥尔摩大学）合作，使用生物测定法确定相应肽序列在体内的插入倾向。然后，我们将应用我们的发现来评估单跨膜蛋白的天然跨膜序列中类似的系统序列变化。******本研究将定义膜蛋白折叠和功能中结构-功能关系的关键原理。我们的总体结果将为细胞膜环境中肽和蛋白质相互作用的性质提供丰富的基础信息。

Conformational transitions of membrane-spanning peptides******Embedded in the membranes of all living cells, membrane proteins are the molecular links between the inside and outside world. These proteins, which represent 20-30% of all human genes, and 70% of drug targets approved by the FDA in the past decade, regulate molecular traffic and information flow across biological lipid bilayers. Given that critical mutations in membrane proteins underlie the causes of many human diseases, efforts to understand and control their structures are of great interest in basic and applied research. ******Mutations in membrane proteins can be regarded as biophysical events that influence not only packing and electrostatic interactions of membrane-spanning helices critical for function, but as well the compatibility of a given protein segment with the lipid bilayer environment of the cell. Our research thus focuses on the protein segments that constitute the basic components of membrane proteins. Under NSERC-funded research, for which the present application is a renewal, we have advanced the use of molecular design, chemical synthesis, and biochemical and biophysical approaches to unravel the code' as to how a given sequence is selected by a cell for membrane insertion, how the receiving lipid environment acts to stabilize the inserted segments, and ultimately how a change in a single amino acid can drastically alter a protein's biological fate. Building on this foundation, we propose to design and chemically synthesize several series of compositionally identical peptides to produce sequences of identical composition, but with varying placement and balance of hydrophobic and polar residues. We will assess peptide-lipid interactions by biochemical techniques such as gel electrophoresis and circular dichroism spectroscopy. In parallel, we will collaborate with Prof. Gunnar von Heijne (Stockholm University) a world expert in membrane protein structure to use a biological assay to determine the insertion propensity of the corresponding peptide sequences in vivo. We will then apply our findings to assess similar systematic sequence variations in the native transmembrane sequence of a single-spanning membrane protein.******This research will define key principles about structure-function relationships in membrane protein folding and function. Our overall results will provide a wealth of fundamental information as to the nature of peptide- and protein interactions in membrane environments.