Department of Bioscience and Biotechnology, Konkuk University, Seoul 05029, Korea.
Magnetic Resonance Team, Korea Basic Science Institute, Ochang 28199, Korea.
Int J Mol Sci. 2020 Apr 9;21(7):2600. doi: 10.3390/ijms21072600.
, a deep-branching hyperthermophilic bacterium, expresses an extraordinarily stable acyl carrier protein (-ACP) that functions as a carrier in the fatty acid synthesis system at near-boiling aqueous environments. Here, to understand the hyperthermal adaptation of -ACP, we investigated the structure and dynamics of -ACP by nuclear magnetic resonance (NMR) spectroscopy. The melting temperature of -ACP (101.4 °C) far exceeds that of other ACPs, owing to extensive ionic interactions and tight hydrophobic packing. The D59 residue, which replaces Pro/Ser of other ACPs, mediates ionic clustering between helices III and IV. This creates a wide pocket entrance to facilitate the accommodation of long acyl chains required for hyperthermal adaptation of the cell membrane. -ACP is revealed to be the first ACP that harbor an amide proton hyperprotected against hydrogen/deuterium exchange for I15. The hydrophobic interactions mediated by I15 appear to be the key driving forces of the global folding process of -ACP. Our findings provide insights into the structural basis of the hyperthermal adaptation of ACP, which might have allowed to survive in hot ancient oceans.
，一种深分枝嗜热菌，表达了一种异常稳定的酰基载体蛋白（ACP），在接近沸腾的水相环境中作为脂肪酸合成系统中的载体发挥作用。在这里，为了了解 ACP 的高热适应特性，我们通过核磁共振（NMR）光谱研究了 ACP 的结构和动力学。ACP 的熔点（101.4°C）远高于其他 ACP，这归因于广泛的离子相互作用和紧密的疏水堆积。取代其他 ACP 中的 Pro/Ser 的 D59 残基介导了 III 螺旋和 IV 螺旋之间的离子聚集。这就形成了一个宽阔的口袋入口，有利于容纳长链酰基，从而实现细胞膜的高热适应。ACP 被揭示是第一个拥有酰胺质子免受氢/氘交换的 ACP，对于 I15 来说是如此。由 I15 介导的疏水相互作用似乎是 ACP 整体折叠过程的关键驱动力。我们的研究结果为 ACP 的高热适应的结构基础提供了深入了解，这可能使 能够在炎热的古代海洋中生存。
