TMAO: Protecting proteins from feeling the heat
TMAO: Protecting proteins from feeling the heat
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TMAO：保护蛋白质免受热量影响
DOI：
10.1016/j.bpj.2023.03.008
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发表时间：
2023
影响因子：
3.4
通讯作者：
Pogorelov, Taras V.
中科院分区：
文献类型：
--
作者：
Boob, Mayank M.;Sukenik, Shahar;Gruebele, Martin;Pogorelov, Taras V.
渗透剂在细胞中普遍存在，在控制应激下蛋白质的稳定性方面发挥着重要作用。海洋动物使用天然渗透剂三甲胺 N-氧化物 (TMAO) 来抵消大深度压力变性的影响。 TMAO 稳定压力和尿素变性的分子机制已被广泛研究，但与其他渗透剂的情况不同，TMAO 保护蛋白质免受高温影响的能力尚未量化。为了揭示 TMAO 在不同温度下对折叠和展开的蛋白质整体以及水合壳的影响，我们研究了特征良好的快速折叠模型蛋白 B (PRB) 的突变体。我们总共对 PRB 在多种温度和 TMAO 浓度下的热折叠/展开进行了 >190μs 的全原子模拟。模拟显示，在 TMAO 存在下，PRB 的热稳定性有所提高。部分结构化、紧凑的整体比展开状态更受青睐。 TMAO 在蛋白质附近形成两个壳：远离蛋白质表面的外壳改变了水分子的氢键寿命，并增加了蛋白质的水合以帮助稳定它；一个较少的内壳，具有相反的TMAO方向，更靠近蛋白质表面，专门与碱性侧链结合。内壳和外壳TMAO的协同共质效应使少量TMAO分子将水分子“聚集”到蛋白质表面或附近的两个水化壳中。尽管 TMAO 溶解度较高，但 TMAO 对蛋白质的稳定作用在 1 M 时饱和，因此，如果一般情况下确实如此，那么极端微生物产生更高细胞内 TMAO 浓度的进化压力可能很小。
Osmolytes are ubiquitous in the cell and play an important role in controlling protein stability under stress. The natural osmolyte trimethylamine N-oxide (TMAO) is used by marine animals to counteract the effect of pressure denaturation at large depths. The molecular mechanism of TMAO stabilization against pressure and urea denaturation has been extensively studied, but unlike the case of other osmolytes, the ability of TMAO to protect proteins from high temperature has not been quantified. To reveal the effect of TMAO on folded and unfolded protein ensembles and the hydration shell at different temperatures, we study a mutant of the well-characterized, fast-folding model protein B (PRB). We carried out, in total, >190μs all-atom simulations of thermal folding/unfolding of PRB at multiple temperatures and concentrations of TMAO. The simulations show increased thermal stability of PRB in the presence of TMAO. Partly structured, compact ensembles are favored over the unfolded state. TMAO forms two shells near the protein: an outer shell away from the protein surface has altered H-bond lifetimes of water molecules and increases hydration of the protein to help stabilize it; a less-populated inner shell with an opposite TMAO orientation closer to the protein surface binds exclusively to basic side chains. The cooperative cosolute effect of the inner and outer shell TMAO has a small number of TMAO molecules "herding" water molecules into two hydration shells at or near the protein surface. The stabilizing effect of TMAO on our protein saturates at 1 M despite higher TMAO solubility, so there may be little evolutionary pressure for extremophiles to produce higher intracellular TMAO concentrations, if true in general.