Collaborative Research on the Molecular Functions of the Signal Sequence in Protein Export

这是细菌遗传学家（Silhavy博士）和物理化学家（Gierasch博士）合作项目的一部分，目的是研究蛋白质输出中信号序列的分子功能。大多数输出蛋白最初都是以氨基末端信号序列的前体形式合成的。已经提出了令人信服的证据，证明这一顺序在出口过程中发挥了重要作用。然而，其功能的细节尚不清楚。由于其体积小（15-30个氨基酸），这种输出信号特别适合使用现代遗传和物理技术进行分析，例如指定杂交蛋白的基因融合，使用合成寡核苷酸的位点特异性诱变，固态肽合成，以及荧光能量在模型膜系统中的传递和猝灭。这些研究人员先前的实验室结果表明，信号序列的内在物理化学性质与其体内功能相关。该项目将扩展和扩大正在进行的跨学科方法，以剖析输出蛋白质的信号序列与生物膜相互作用的分子机制。这一目标将通过使用出口缺陷的大肠杆菌突变株，其中外膜蛋白LamB的信号序列被改变，并通过相应的合成信号肽的物理化学研究来促进。

This is part of a collaborative project between a bacterial geneticist (Dr. Silhavy) and a physical chemist (Dr. Gierasch) to study the molecular functions of the signal sequence in protein export. Most exported proteins are synthesized initially in precursor form with an amino-terminal signal sequence. Convincing evidence demonstrating the essential role of this sequence in the export process has been presented. However, details of its function(s) are not well understood. Because of its small size (15-30 amino acids), this export signal is particularly amenable to analysis using modern genetic and physical techniques, such as gene fusions that specify hybrid proteins, site-specific mutagenesis using synthetic oligonucleotides, solid-state peptide synthesis, and fluorescence enregy transfer and quenching in model membrane systems. Previous results from the laboratories of these researchers demonstrated that intrinsic physical-chemical properties of the signal sequence are correlated with its in vivo function. This project will expand and amplify the ongoing interdisciplinary approach to dissect the molecular mechanism by which the signal sequence of exported proteins interacts with a biological membrane. This goal will be facilitated through the use of export-defective mutant strains of E. coli in which the signal sequence of the outer membrane protein, LamB, is altered, and through the physical-chemical study of corresponding synthetic signal peptides.