5′-Adenosinephosphosulphate reductase (CysH) protects Mycobacterium tuberculosis against free radicals during chronic infection phase in mice
5′-Adenosinephosphosulphate reductase (CysH) protects Mycobacterium tuberculosis against free radicals during chronic infection phase in mice
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DOI：
10.1111/j.1365-2958.2006.05075.x
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发表时间：
2006-03-01
影响因子：
3.6
通讯作者：
Riley, LW
中科院分区：
文献类型：
--
作者：
Senaratne, RH;De Silva, AD;Riley, LW
结核病（TB）控制的一个主要障碍是慢性结核感染（CTBI）问题。在此，我们报告5'-磷酸腺苷还原酶（CysH）是产生含还原硫代谢物所必需的酶，对于小鼠慢性感染阶段结核分枝杆菌（Mtb）的存活至关重要。 cysH 的破坏使 Mtb 的半胱氨酸和蛋氨酸营养缺陷，并减弱了 BALB/c 和 C57BL/6 免疫活性小鼠的毒力。突变型和野生型结核分枝杆菌在感染的急性期复制相似，但突变型在感染的持续期表现出活力降低。 cysH 突变体在四组不同的小鼠（Rag1(-/-)、NOS2(-/-)、gp91phox(-/-) NOS2(-/-) 和 gp91phox(-/-) 小鼠）感染 4-7 周后引起疾病和死亡，这些小鼠给予氨基胍[以抑制一氧化氮合酶 2 (NOS2) 的作用]，表明这些小鼠中 cysH 突变体存活的代谢影响极小。 cysH 突变体在体外也对过氧亚硝酸盐和过氧化氢敏感。这些结果表明CysH对于Mtb在慢性感染阶段的保护很重要，并且抵抗亚硝化和氧化应激可能是这种保护的机制。因此，细胞内病原体的这种代谢基因可能在抵御宿主免疫反应方面发挥次要作用。最后，由于缺乏 cysH 的内源性人类直系同源物及其在防御适应性免疫中的可能作用，使得 CysH 成为一种有吸引力的酶，可作为针对 CTBI 的活性治疗的靶点进行进一步研究。
A major obstacle to tuberculosis (TB) control is the problem of chronic TB infection (CTBI). Here we report that 5'-adenosinephosphosulphate reductase (CysH), an enzyme essential for the production of reduced-sulphur-containing metabolites, is critical for Mycobacterium tuberculosis (Mtb) survival in chronic infection phase in mice. Disruption of cysH rendered Mtb auxotrophic for cysteine and methionine, and attenuated virulence in BALB/c and C57BL/6 immunocompetent mice. The mutant and wild-type Mtb replicated similarly during the acute phase of infection, but the mutant showed reduced viability during the persistent phase of the infection. The cysH mutant caused disease and death after 4-7 weeks of infection in four different groups of mice - Rag1(-/-), NOS2(-/-), gp91phox(-/-) NOS2(-/-) and gp91phox(-/-) mice given aminoguanidine [to suppress the effects of nitric oxide synthase 2 (NOS2)]- indicating minimal metabolic effect on the cysH mutant survival in these mice. The cysH mutant was also susceptible to peroxynitrite and hydrogen peroxide in vitro. These results show that CysH is important for Mtb protection during the chronic infection phase, and that resistance to nitrosative and oxidative stress may be the mechanism of this protection. Thus, this metabolic gene of an intracellular pathogen could have a secondary role in protection against the host immune response. Finally the lack of an endogenous human orthologue of cysH and its possible role in defence against adaptive immunity renders CysH an attractive enzyme for further studies as a target for therapeutics active against CTBI.