Acidic pH irreversibly activates the signaling enzyme SARM1
Acidic pH irreversibly activates the signaling enzyme SARM1
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DOI：
10.1111/febs.16104
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发表时间：
2021-07-13
期刊：
影响因子：
5.4
通讯作者：
Zhang, Dapeng
中科院分区：
文献类型：
--
作者：
Zhao, Yong Juan;He, Wei Ming;Zhang, Dapeng
Sarm1是轴突变性的执行者，是一种自身抑制的NAD消耗酶，由多个结构域组成。NMN及其类似物CZ-48和VMN是唯一已知的能够从酶TIR结构域中释放抑制臂结构域的激活剂。在这里，我们记录了酸也可以激活Sarm1，甚至比NMN更有效，可能是通过负残基的质子化。系统诱变表明，TIR中的一个突变E689Q导致了Sarm1的结构性激活。它与相邻臂上的R216形成盐桥，维持自抑制结构。利用这种“酸激活”程序，突变K597E抑制激活，而H685A消除Sarm1的催化活性，揭示了两种不同的抑制机制。该协议还被用于区分两类化学缓蚀剂。NAD、dHNN、双硫仑、CHAPS和TRX-100主要抑制激活过程，烟酰胺和Tweens主要抑制Sarm1催化。综上所述，我们展示了一种新的Sarm1激活机制，并破译了Sarm1的两种不同的抑制机制。
SARM1, an executioner in axon degeneration, is an autoinhibitory NAD-consuming enzyme, composed of multiple domains. NMN and its analogs, CZ-48 and VMN, are the only known activators, which can release the inhibitory ARM domain from the enzymatic TIR domain. Here, we document that acid can also activate SARM1, even more efficiently than NMN, possibly via the protonation of the negative residues. Systematic mutagenesis revealed that a single mutation, E689Q in TIR, led to the constitutive activation of SARM1. It forms a salt bridge with R216 in the neighboring ARM, maintaining the autoinhibitory structure. Using this 'acid activation' protocol, mutation K597E was found to inhibit activation, while H685A eliminated SARM1 catalytic activity, revealing two distinct inhibitory mechanisms. The protocol has also been applied to differentiate two classes of chemical inhibitors. NAD, dHNN, disulfiram, CHAPS, and TRX-100 mainly inhibited the activation process, while nicotinamide and Tweens mainly inhibited SARM1 catalysis. Taken together, we demonstrate a new mechanism for SARM1 activation and decipher two distinct inhibitory mechanisms of SARM1.