STRUCTURE/FUNCTION OF THE LEUCINE ZIPPER MOTIF

这项研究计划的广泛和长期目标是了解 蛋白质相互作用的基础。重点是螺旋线圈 在DNA结合蛋白的“亮氨酸拉链”类中发现。 将这些研究扩展到在tRNA中发现的反平行卷曲螺旋 合成酶和“螺旋-环-螺旋”类转录因子的结合是 并提出了该方法包括蛋白质的结构解剖 这些模块显示要检查的基本功能。 研究的具体目标是： (1)评价氢键离子对对稳定性的贡献 (i.e.,盐桥）在二聚体、三聚体和 来自GCN 4的亮氨酸拉链的四聚体（酵母转录因子 激活剂），以了解决定 蛋白质中静电相互作用的强度。 (2)表征各种GCN 4亮氨酸拉链的溶液性质 肽，与许多技术，包括核磁共振 (NMR)光谱和酰胺质子交换，以了解 蛋白质结构独特性的决定因素。 (3)为了确定反平行卷曲螺旋形成的机制， 对应于丝氨酰tRNA合成酶片段的肽， 为了了解影响平行与 α-螺旋的反平行取向。 (4)为了将我们对转录因子模块的研究扩展到 螺旋-环-螺旋（HLH）基序，其有时被发现邻近于 转录因子的亮氨酸拉链区，包括核 癌蛋白Myc和Max. 蛋白质之间的相互作用是许多生理学的核心。许多 这里研究的蛋白质片段来自医学上的 重要蛋白质因此，这些研究有助于增加 理解转录、翻译、发育和肿瘤发生。 这项工作也直接关系到一些中心问题， 蛋白质折叠，这仍然是一个主要的未解决的问题，在分子 生物学

The broad, long-term objective of this research plan is to understand the basis of protein-protein interactions. The focus is on coiled-coil interactions, found in the "leucine-zipper" class of DNA-binding proteins. Extension of these studies to the antiparallel coiled coil found in a tRNA synthetase and to the "helix-loop-helix" class of transcription factors is also proposed. The methodology involves structural dissection of proteins into modules that display the essential features to be examined. The specific aims of the research are: (1) To evaluate the contributions to stability of H-bonded ion pairs (i.e., salt bridges) in the crystal structures of the dimer, trimer and tetramer of the leucine zipper from GCN4 (a yeast transcriptional activator), in order to understand the factors that determine the strengths of electrostatic interactions in proteins. (2) To characterize the solution properties of various GCN4 leucine-zipper peptides, with numerous techniques including nuclear magnetic resonance (NMR) spectroscopy and amide proton exchange, in order to understand the determinants of uniqueness in protein structures. (3) To determine the mechanism for antiparallel coiled-coil formation by peptides that correspond to a segment of the seryl tRNA synthetase, in order to understand the factors that influence parallel versus antiparallel orientation of alpha-helices. (4) To extend our studies of the transcription-factor modules to the helix-loop-helix (HLH) motif, which is sometimes found adjacent to the leucine-zipper region of transcription factors, including the nuclear oncoproteins Myc and Max. The interaction between proteins is central to much of physiology. Many of the protein fragments that are studied here are derived from medically important proteins. As a result, these studies contribute to an increased understanding of transcription, translation, development, and oncogenesis. This work is also directly relevant to some of the central issues in protein folding, which remains a major unsolved problem in molecular biology.