Common Crowding Agents Have Only a Small Effect on Protein-Protein Interactions
Common Crowding Agents Have Only a Small Effect on Protein-Protein Interactions
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DOI：
10.1016/j.bpj.2009.05.026
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发表时间：
2009-08-05
影响因子：
3.4
通讯作者：
Schreiber, Gideon
中科院分区：
文献类型：
--
作者：
Phillip, Yael;Sherman, Eilon;Schreiber, Gideon
在聚合物溶液中进行的蛋白质-蛋白质相互作用的研究旨在模拟活细胞内的拥挤环境。结果表明，拥挤促进低聚和聚合的大分子。相反，我们已经表明，拥挤对蛋白质复合物的缔合速率只有很小的影响。在这里，我们研究了拥挤对TEM 1-β-内酰胺酶与Q-内酰胺酶抑制蛋白（BLIP）和芽孢杆菌RNA酶与芽孢杆菌RNA酶抑制蛋白（Barstar）的蛋白质异二聚体的平衡效应。我们还将这些与拥挤对弱结合对CyPet-YPet的影响进行了对比。我们测量的协会和解离速率，以及这些相互作用在聚乙二醇和葡聚糖溶液中的亲和力和热力学参数。对于TEM 1-BLIP和barnase-barstar，与基于溶液粘度的预期结果相比，缔合速率常数只有轻微的降低，解离速率常数显示出类似的降低水平。总体而言，这导致与水溶液中的结合亲和力非常相似的结合亲和力。另一方面，对于CyPet-YPet对，在聚乙二醇溶液中检测到聚集而不是增强的二聚化。结果表明，典型的拥挤剂对特定的蛋白质-蛋白质二聚化反应只有很小的影响。尽管细胞中的拥挤是由蛋白质和其他大分子引起的，但人们仍然可以推测体内结合与在稀溶液中测量的结合没有很大不同。
Studies of protein-protein interactions, carried out in polymer solutions, are designed to mimic the crowded environment inside living cells. It was shown that crowding enhances oligomerization and polymerization of macromolecules. Conversely, we have shown that crowding has only a small effect on the rate of association of protein complexes. Here, we investigated the equilibrium effects of crowding on protein heterodimerization of TEM1-beta-lactamase with,Q-lactamase inhibitor protein (BLIP) and barnase with barstar. We also contrasted these with the effect of crowding on the weak binding pair CyPet-YPet. We measured the association and dissociation rates as well as the affinities and thermodynamic parameters of these interactions in polyethylene glycol and dextran solutions. For TEM1-BLIP and for barnase-barstar, only a minor reduction in association rate constants compared to that expected based on solution viscosity was found. Dissociation rate constants showed similar levels of reduction. Overall, this resulted in a binding affinity that is quite similar to that in aqueous solutions. On the other hand, for the CyPet-YPet pair, aggregation, and not enhanced dimerization, was detected in polyethylene glycol solutions. The results suggest that typical crowding agents have only a small effect on specific protein-protein dimerization reactions. Although crowding in the cell results from proteins and other macromolecules, one may still speculate that binding in vivo is not very different from that measured in dilute solutions.