Adaptive MscS gating in the osmotic permeability response in E. coli: the question of time.
Adaptive MscS gating in the osmotic permeability response in E. coli: the question of time.
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DOI：
10.1021/bi1019435
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发表时间：
2011-05-17
期刊：
影响因子：
2.9
通讯作者：
Sukharev S
中科院分区：
文献类型：
--
作者：
Boer M;Anishkin A;Sukharev S
微生物通过机械敏感（MS）通道释放小的渗透压调节剂来适应渗透压降低。我们想了解小机械敏感通道（MscS）的激活和失活，都是由膜张力驱动，在不同的低渗休克情况下优化生存。通过用停流装置测量光散射，我们估计细菌溶胀时间为30-50 ms。部分溶质平衡在150-200 ms内，在此期间，WT MscS细胞的光学响应偏离缺乏MS通道的细胞。在膜片钳估计MSCS开放率显示通道容易响应低于溶解极限的张力，时间过程快于20 ms，并在张力释放后迅速关闭。为了解决张力不敏感的失活状态在体内的作用，我们应用短，长和两步渗透压休克协议WT，非失活G113 A和快速失活D 62 N突变体。WT和G113 A在短的1 min 800 mOsm下电击实验中表现出相当的存活率，但G113 A在长的60 min下电击实验中处于不利地位。携带WT MscS的预休克细胞15秒至15分钟，200 mOsm下调，不会使它们对第二步的渗透压摩尔浓度的最终500 mOsm下降敏感。然而，这些两步电击诱导的D 62 N死亡不仅仅是一步700 mOsm降档。我们的结论是MscS能够激活和渗出渗透压比溶解压力建立在细胞内突然休克。在长时间的电击过程中，逐渐失活会阻止持续的通道活动并有助于恢复。WT MscS中失活的缓慢动力学确保了轻度休克不会使整个群体死亡，从而在病情恶化时留下一些保护。
Microorganisms adapt to osmotic downshifts by releasing small osmolytes through mechanosensitive (MS) channels. We want to understand how the small mechanosensitive channel’s (MscS) activation and inactivation, both driven by membrane tension, optimize survival in varying hypoosmotic shock situations. By measuring light scattering with a stopped-flow device, we estimate bacterial swelling time as 30-50 ms. A partial solute equilibration follows within 150-200 ms, during which optical responses from cells with WT MscS deviate from those lacking MS channels. MscS opening rates estimated in patch-clamp show the channels readily respond to tensions below the lytic limit with a time course faster than 20 ms and close promptly upon tension release. To address the role of the tension-insensitive inactivated state in vivo, we applied short, long and two-step osmotic shock protocols to WT, noninactivating G113A and fast-inactivating D62N mutants. WT and G113A showed a comparable survival in short 1 min 800 mOsm downshock experiments, but G113A was at a disadvantage under a long 60 min shock. Pre-shocking cells carrying WT MscS for 15 s to 15 minutes with a 200 mOsm downshift did not sensitize them to the final 500 mOsm drop in osmolarity of the second step. However, these two-step shocks induced death in D62N more than just a one-step 700 mOsm downshift. We conclude MscS is able to activate and exude osmolytes faster than lytic pressure builds inside the cell under abrupt shock. During prolonged shocks, gradual inactivation prevents continuous channel activity and assists recovery. Slow kinetics of inactivation in WT MscS ensures that mild shocks do not inactivate the entire population, leaving some protection should conditions worsen.
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影响因子：
11.4
作者：
Li, YZ;Moe, PC;Blount, P
通讯作者：
Blount, P
DOI：
10.1073/pnas.1001405107
发表时间：
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影响因子：
11.1
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影响因子：
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作者：
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通讯作者：
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DOI：
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发表时间：
2010-06
期刊：
The Journal of general physiology
影响因子：
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作者：
Belyy V;Kamaraju K;Akitake B;Anishkin A;Sukharev S
通讯作者：
Sukharev S
DOI：
10.1085/jgp.200409198
发表时间：
2005-02
期刊：
The Journal of general physiology
影响因子：
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作者：
Akitake B;Anishkin A;Sukharev S
通讯作者：
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