The Mycobacterium tuberculosis proteasome active site threonine is essential for persistence yet dispensable for replication and resistance to nitric oxide.
The Mycobacterium tuberculosis proteasome active site threonine is essential for persistence yet dispensable for replication and resistance to nitric oxide.
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DOI：
10.1371/journal.ppat.1001040
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发表时间：
2010-08-12
期刊：
影响因子：
6.7
通讯作者：
Ehrt S
中科院分区：
文献类型：
--
作者：
Gandotra S;Lebron MB;Ehrt S
以前的工作表明，有条件的核心蛋白酶体亚基PrcB和PrcA的耗竭损害结核分枝杆菌在体外和小鼠肺中的生长，引起对一氧化氮（NO）的过敏性和慢性小鼠感染过程中杆菌的持久性受损。在这里，我们表明，基因缺失prcBA导致类似的表型。然而，令人惊讶的是，活性位点突变蛋白酶体补充了prcBA敲除（ΔprcBA）的体外和体内生长缺陷及其NO超敏性。相反，M.在静止期和体外饥饿期间以及在小鼠感染的慢性期，结核病需要具有蛋白水解活性的蛋白酶体。诱导型一氧化氮合酶的抑制并不能挽救ΔprcBA的存活，揭示了一种超越NO防御的功能，通过这种功能，蛋白酶体有助于M。慢性小鼠感染期间的结核病适应性。这些发现表明，蛋白酶体的蛋白水解促进分枝杆菌的持久性，M。结核病在慢性小鼠感染期间面临饥饿，并且蛋白酶体具有不依赖于蛋白水解的功能。真核生物的蛋白酶体是普遍存在的，并且对于许多基本的细胞过程是必需的。与大多数不表达蛋白酶体的细菌相反，结核分枝杆菌编码预测为病原体的最佳生长所必需或需要的蛋白酶体。蛋白酶体核心基因的遗传沉默进一步表明，M。结核蛋白酶体在抵抗一氧化氮和在慢性小鼠感染期间病原体的持续存在中起重要作用。在这篇文章中，我们产生了一个蛋白酶体核心基因的遗传缺失突变体，证明20 S蛋白酶体对M.结核我们补充了蛋白酶体敲除与蛋白水解活性和突变，蛋白水解缺陷的蛋白酶体。这表明，蛋白酶体蛋白水解是在体外和体内的生长和一氧化氮抗性的M。结核病，并表明蛋白酶体核心服务的蛋白水解独立的功能。相反，病原体在体外和小鼠感染的慢性期的长期存活需要具有蛋白水解活性的蛋白酶体。我们进一步提供证据表明，一氧化氮是不负责杀死蛋白酶体敲除在慢性小鼠感染。因此，蛋白酶体的蛋白水解促进分枝杆菌的持久性独立防御一氧化氮。我们认为，M.在慢性感染期间缺乏蛋白水解活性蛋白酶体的结核病。
Previous work revealed that conditional depletion of the core proteasome subunits PrcB and PrcA impaired growth of Mycobacterium tuberculosis in vitro and in mouse lungs, caused hypersusceptibility to nitric oxide (NO) and impaired persistence of the bacilli during chronic mouse infections. Here, we show that genetic deletion of prcBA led to similar phenotypes. Surprisingly, however, an active site mutant proteasome complemented the in vitro and in vivo growth defects of the prcBA knockout (ΔprcBA) as well as its NO hypersensitivity. In contrast, long-term survival of M. tuberculosis in stationary phase and during starvation in vitro and in the chronic phase of mouse infection required a proteolytically active proteasome. Inhibition of inducible nitric oxide synthase did not rescue survival of ΔprcBA, revealing a function beyond NO defense, by which the proteasome contributes to M. tuberculosis fitness during chronic mouse infections. These findings suggest that proteasomal proteolysis facilitates mycobacterial persistence, that M. tuberculosis faces starvation during chronic mouse infections and that the proteasome serves a proteolysis-independent function. The eukaryotic proteasome is ubiquitous and essential for many basic cellular processes. In contrast to most bacteria, which do not express a proteasome, Mycobacterium tuberculosis encodes a proteasome predicted to be essential or required for optimal growth of the pathogen. Genetic silencing of the proteasome core genes further suggested that the M. tuberculosis proteasome plays an important role in defense against nitric oxide and in persistence of the pathogen during chronic mouse infections. In this manuscript we generated a genetic deletion mutant of the proteasome core genes proving that the 20S proteasome is not essential for growth of M. tuberculosis. We complemented the proteasome knockout with a proteolytically active and a mutated, proteolysis defective proteasome. This revealed that proteasomal proteolysis is dispensable for in vitro and in vivo growth and nitric oxide resistance of M. tuberculosis and suggests that the proteasome core serves a proteolysis-independent function. In contrast, long-term survival of the pathogen in vitro and in the chronic phase of mouse infection required a proteolytically active proteasome. We further provide evidence that nitric oxide is not responsible for killing of the proteasome knockout during chronic mouse infections. Thus, proteasomal proteolysis facilitates mycobacterial persistence independently of defense against nitric oxide. We propose that the failure to survive starvation contributes to the impaired persistence of M. tuberculosis lacking a proteolytically active proteasome during chronic infections.
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影响因子：
3.6
作者：
Hu, GQ;Lin, G;Li, HL
通讯作者：
Li, HL
影响因子：
56.9
作者：
Darwin, KH;Ehrt, S;Nathan, CF
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作者：
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DOI：
10.1073/pnas.1631248100
发表时间：
2003-08-19
影响因子：
11.1
作者：
Dahl, JL;Kraus, CN;Barry, CE
通讯作者：
Barry, CE
影响因子：
4.8
作者：
Kisselev, AF;Songyang, Z;Goldberg, AL
通讯作者：
Goldberg, AL