Structural Constraints on Subunit Assembly

0078363 Baldwin，B.A.通常认为，作为多亚基复合物组分起作用的多肽具有相同的结构，无论是在复合物中还是作为游离亚基。 这一建议所依据的假设是，这种观点一般来说并不准确。 该PI表明复合物中亚基的构象可能仅代表游离亚基的平衡群体中存在的构象的一部分。 支持这一假设的事实是，多亚基复合物组装的相关速率常数跨越许多数量级的值。 通过本提案中描述的实验，PI期望发现荧光素酶亚基缔合速率的动力学异质性。 缔合速率的差异将是不同结构的证据，并且不同速率分量的相对幅度将允许对构象异构体的相对群体进行定量描述。 在这些实验的第二阶段，PI将确定构象异构体的数量在多大程度上可以被溶液条件和遗传突变所改变。活细胞中所有多肽的大部分在多亚基复合物中起作用。 这些复合物组装的基本机制知之甚少。 在络合物形成的能量学方面已经有了大量的工作，但在形成和解离的速率方面相对较少。 蛋白质-蛋白质相互作用在许多基本生命过程中起着至关重要的作用。 本项目的研究旨在对多亚基蛋白质的动力学性质获得更详细和基本的了解。

0078363Baldwin, ThomasIt is commonly assumed that polypeptides that function as components of multisubunit complexes have the same structure, whether in the complex or as the free subunit. The hypothesis upon which this proposal is based is that this view is not generally accurate. This PI suggest that the conformation of the subunit in the complex may represent only a fraction of the conformations present in an equilibrium population of the free subunits. In support of this hypothesis is the fact that the associate rate constants for assembly of multisubunit complexes span many orders of magnitude in value. Through the experiments described in this proposal, the PI expects to find kinetic heterogeneity in associate rates for the luciferase subunits. Differences in association rates will be evidence for differing structures, and the relative amplitudes of the different rate components will allow quantitative description of the relative populations of conformers. In the second phase of these experiments, the PI will ascertain the extent to which the populations of conformers may be altered by solution conditions and by genetic mutation.A large proportion of all polypeptides in living cells function within multisubunit complexes. The fundamental mechanisms through which these complexes assemble are very poorly understood. There has been extensive work on the energetics of complex formation, but relatively little on the rates of formation and dissociation. Protein-protein interactions play crucial roles in many fundamental life processes. The research of this project is designed to obtain a more detailed and fundamental understanding of the dynamic nature of multisubunit proteins.