Sanfelice Domenico, Morandi Edoardo, Pastore Annalisa, Niccolai Neri, Temussi Piero Andrea
Department of Basic and Clinical Neurosciences, Kings College London, London, SE5 9RX, UK.
Department of Biotechnology, Chemistry and Pharmacy, University of Siena, 53100, Siena, Italy.
Chemphyschem. 2015 Dec 1;16(17):3599-602. doi: 10.1002/cphc.201500765. Epub 2015 Oct 14.
What is the mechanism that determines the denaturation of proteins at low temperatures, which is, by now, recognized as a fundamental property of all proteins? We present experimental evidence that clarifies the role of specific interactions that favor the entrance of water into the hydrophobic core, a mechanism originally proposed by Privalov but never proved experimentally. By using a combination of molecular dynamics simulation, molecular biology, and biophysics, we identified a cluster of negatively charged residues that represents a preferential gate for the entrance of water molecules into the core. Even single-residue mutations in this cluster, from acidic to neutral residues, affect cold denaturation much more than heat denaturation, suppressing cold denaturation at temperatures above zero degrees. The molecular mechanism of the cold denaturation of yeast frataxin is intrinsically different from that of heat denaturation.
低温下蛋白质变性的机制是什么？目前，这已被公认为是所有蛋白质的一项基本特性。我们提供的实验证据阐明了特定相互作用的作用，这种相互作用有利于水进入疏水核心，这是普里瓦洛夫最初提出的一种机制，但从未得到实验证明。通过结合分子动力学模拟、分子生物学和生物物理学，我们确定了一组带负电荷的残基，它们是水分子进入核心的优先通道。即使该簇中的单个残基从酸性突变为中性残基，对冷变性的影响也远大于对热变性的影响，在高于零度的温度下抑制冷变性。酵母frataxin冷变性的分子机制与热变性的本质不同。
