Direct high-pressure NMR observation of dipicolinic acid leaking from bacterial spore: A crucial step for thermal inactivation
Direct high-pressure NMR observation of dipicolinic acid leaking from bacterial spore: A crucial step for thermal inactivation
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DOI：
10.1016/j.bpc.2017.04.008
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发表时间：
2017-12-01
影响因子：
3.8
通讯作者：
Yamazaki, Akira
中科院分区：
文献类型：
--
作者：
Akasaka, Kazuyuki;Maeno, Akihiro;Yamazaki, Akira
细菌孢子用异常高浓度（类似于孢子干重的10%）的吡啶二羧酸（DPA）保护自身，其释放被认为是在温和的压力和温度条件下使其失活的关键步骤。然而，孢子如何响应压力释放DPA的过程仍然不清楚。本文首次将H-1高分辨率高压NMR光谱应用于纳豆芽孢杆菌孢子悬浮液，并直接实时监测DPA在20 ℃、200 MPa压力下的泄漏过程。我们发现，约三分之一的总DPA泄漏后立即施加压力，但其余的缓慢泄漏小时后，降低压力。一旦DPA从孢子中完全释放，孢子的蛋白质在温和的温度下变得容易变性，例如，80摄氏度，远低于通常用于培养孢子的温度（121摄氏度）。本实验的成功为在分子水平上研究细菌孢子和细胞对压力、温度和其他扰动的反应开辟了新的途径。
A bacterial spore protects itself with an unusually high concentration (similar to 10% in dry weight of spore) of dipicolinic acid (DPA), the release of which is considered the crucial step for inactivating it under mild pressure and temperature conditions. However, the process of how the spore releases DPA in response to pressure remains obscure. Here we apply H-1 high-resolution high-pressure NMR spectroscopy, for the first time, to the spore suspension of Bacillus subtilis natto and monitor directly and in real-time the leaking process of DPA in response to pressure of 200 MPa at 20 degrees C. We find that about one third of the total DPA leaks immediately upon applying pressure, but that the rest leaks slowly in hrs upon decreasing the pressure. Once DPA is fully released from the spore, the proteins of the spore become easily denatured at a mild temperature, e.g., 80 degrees C, much below the temperature commonly used to inactivate spores (121 degrees C). The success of the present experiment opens a new avenue for studying bacterial spores and cells at the molecular level in response to pressure, temperature and other perturbations.