Structure and Interactions of Gas Vesicles by SSNMR

描述（由申请人提供）：尽管对其非凡的特性非常感兴趣，并且多年来几个小组带来了相当大范围的专业知识，但只有气体囊泡结构的最一般特征是已知的。然而，最近的研究进展是固态核磁共振，为7kDa单体gvpA结构的原子细节提供了许多独特的探针，并将其组装成坚硬的淀粉样壳。均匀标记的囊泡的初步13C和15N光谱表明，几种同位素标记策略和一系列多维相关实验的结合应该允许完整的共振分配和确定单体内和单体间的结构约束。最终，这些信息将使气体囊泡外壳的完整结构得以确定。研究工作将同时进行，研究来自古咸水盐杆菌和藻蓝藻的气囊。由于两种生物的gvpA之间具有很强的核心同源性，并且两种生物中可用的同位素标记策略不同，因此平行的努力将是协同的。由于两种gvpA序列的N端和c端结构域的差异导致整体囊泡形态的差异，这种平行的努力也将是互补的。静电的作用将通过确定阳离子位移和质子化变化来探索，这些变化会随着ph的降低而诱导囊泡塌陷。对盐的反应也将是有趣的，因为盐芽孢杆菌是一种嗜盐菌，而黄芽孢杆菌适应甜水。发现的结构细节将揭示囊泡的形态和刚性的分子基础，防止水在这些透气性细胞器内凝结，以及控制这些淀粉样聚集体的组装和拆卸。

DESCRIPTION (provided by applicant): Despite great interest in their remarkable properties, and the considerable range of expertise brought to bear by several groups over many years, only the most general features of the structure of gas vesicles are known. However, recent developments now poise solid state NMR to provide numerous unique probes of the atomic details of the structure of the 7kDa monomer, gvpA, and its assembly into rigid, amyloid-like shells. Preliminary 13C and 15N spectra of uniformly labeled vesicles indicate that a combination of several isotope labeling strategies and an array of multidimensional correlation experiments should allow the full assignment of resonances and the determination of both intra-monomer and inter-monomer structural constraints. Ultimately, this information will allow the complete structure of the gas vesicle shell to be determined. Work will be carried out simultaneously on gas vesicles from the archae Halobacterium salinarum and the cyanobacterium Anabaena flos-aquaea. The parallel efforts will be synergistic because of the strong core homology between the gvpA's of the two species and the different isotope labeling strategies available in the two organisms. The parallel efforts will also be complimentary because of differences in overall vesicle morphology associated with differences in the N- and C-terminal domains of the two gvpA sequences. The role of electrostatics will be explored by identifying the cation displacements and protonation changes that induce vesicle collapse with decreasing pH. The response to salt will also be interesting since H. salinarum is a halophile and A. flos-aquaea is adapted to sweet water. Discovered structural details will shed light on the molecular basis of the morphology and rigidity of the vesicles, the prevention of water condensation within these gas permeable organelles, and the controlled assembly and disassembly of these amyloid-like aggregates.