Cellular Protection of SNAP-25 against Botulinum Neurotoxin/A: Inhibition of Thioredoxin Reductase through a Suicide Substrate Mechanism.
Cellular Protection of SNAP-25 against Botulinum Neurotoxin/A: Inhibition of Thioredoxin Reductase through a Suicide Substrate Mechanism.
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DOI：
10.1021/jacs.5b12929
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发表时间：
2016-05-04
影响因子：
15
通讯作者：
Janda KD
中科院分区：
文献类型：
--
作者：
Seki H;Xue S;Pellett S;Šilhár P;Johnson EA;Janda KD
肉毒杆菌神经毒素（BoNTs）是人类已知的最致命的毒素之一。它们由七种血清型组成，BoNT/A是最致命的；然而，目前还没有批准的治疗它们中毒的方法，甚至没有进入临床试验的方法。肉毒杆菌神经毒性最终是通过轻链（LC）蛋白酶SNARE蛋白裂解导致神经递质释放的损失。清除BoNT/A中毒的药理学尝试试图消除细胞毒素进入或在其复杂的作用机制中发现的关键生化连接。在这些方面，非肽类小分子抑制剂的报道已经浮出水面，但很少有证据表明在中和细胞毒性方面有效，这是启动啮齿动物致死率研究的关键先决条件。基于我们在BoNT/ a细胞分析活动中发现的铅，我们基于结构活性关系（SAR）基础研究了n -羟基琥珀酰亚胺抑制剂家族。从这个SAR练习中产生的分子被认为是蛋白酶抑制剂。然而，在广泛的动力学分析的基础上，这个命题被推翻了。出乎意料的是，抑制剂数据指向硫氧还蛋白还原酶（TrxR），这是BoNT蛋白酶易位所需的重要成分。同样不可预见的是抑制剂对TrxR的作用机制，它被发现是通过一种自杀机制来协调的，利用醌类化合物作为灭活元素。这个新的TrxR抑制剂系列提供了一种替代的方法来否定BoNT中毒的病原，LC蛋白酶。
Botulium neurotoxins (BoNTs) are among the most lethal toxins known to man. They are comprised of seven serotypes with BoNT/A being the most deadly; yet, there is no approved therapeutic for their intoxication or one that has even advanced to clinical trials. Botulinum neurotoxicity is ultimately governed through light chain (LC) protease SNARE protein cleavage leading to a loss of neurotransmitter release. Pharmacological attempts to ablate BoNT/A intoxication have sought to either nullify cellular toxin entry or critical biochemical junctions found within its intricate mechanism of action. In these regards, reports have surfaced of nonpeptidic small molecule inhibitors, but few have demonstrated efficacy in neutralizing cellular toxicity, a key prerequisite before rodent lethality studies can be initiated. On the basis of a lead discovered in our BoNT/A cellular assay campaign, we investigated a family of N-hydroxysuccinimide inhibitors grounded upon structure activity relationship (SAR) fundamentals. Molecules stemming from this SAR exercise were theorized to be protease inhibitors. However, this proposition was overturned on the basis of extensive kinetic analysis. Unexpectedly, inhibitor data pointed to thioredoxin reductase (TrxR), an essential component required for BoNT protease translocation. Also unforeseen was the inhibitors’ mechanism of action against TrxR, which was found to be brokered through a suicide-mechanism utilizing quinone methide as the inactivating element. This new series of TrxR inhibitors provides an alternative means to negate the etiological agent responsible for BoNT intoxication, the LC protease.