Characterization of Cu,Zn superoxide dismutase (SOD1) gene knock-out mutant of Cryptococcus neoformans var. gattii:: role in biology and virulence
Characterization of Cu,Zn superoxide dismutase (SOD1) gene knock-out mutant of Cryptococcus neoformans var. gattii:: role in biology and virulence
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DOI：
10.1046/j.1365-2958.2003.03393.x
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发表时间：
2003-03-01
影响因子：
3.6
通讯作者：
Chaturvedi, S
中科院分区：
文献类型：
--
作者：
Narasipura, SD;Ault, JG;Chaturvedi, S
致病性酵母隐球菌新生（Cn）变种。gattii在健康个体中引起脑膜脑炎，这与更好地了解的Cn变种Grubii和neoformans不同，后者在免疫受损个体中是常见的。毒力的决定因素和主机偏好的机制是很难定义的变种。加提。利用DNA转化系统构建了铜锌超氧化物歧化酶（SOD 1）基因敲除突变体。sod1突变体是高度敏感的氧化还原循环剂甲萘醌，并显示在细胞质中的大空泡的碎片，但没有看到其他缺陷的生长，胶囊合成，交配，孢子形成，静止期生存或含硫氨基酸营养缺陷型。在小鼠模型中，sod1突变体的毒力明显减弱，并且对人中性粒细胞（PMNs）的体外杀伤明显敏感。SOD1的缺失也导致了一些毒力因子，即漆酶，尿素酶和磷脂酶的表达缺陷。SOD1突变体与SOD1的互补导致毒力因子表达和甲萘醌抗性的恢复，并恢复毒力。这些结果表明，Cu，Zn SOD的抗氧化功能是至关重要的致病性的真菌，但在其污秽生活是有限的。这份报告构成了超氧化物歧化酶直接参与真菌病原体毒力的第一例。
The pathogenic yeast Cryptococcus neoformans (Cn) var. gattii causes meningoencephalitis in healthy individuals, unlike the better known Cn varieties grubii and neoformans , which are common in immunocompromised individuals. The virulence determinants and mechanisms of host predilection are poorly defined for var. gattii. The present study focused on the characterization of a Cu,Zn superoxide dismutase (SOD1) gene knock-out mutant constructed by developing a DNA transformation system. The sod1 mutant was highly sensitive to the redox cycling agent menadione, and showed fragmentation of the large vacuole in the cytoplasm, but no other defects were seen in growth, capsule synthesis, mating, sporulation, stationary phase survival or auxotrophies for sulphur-containing amino acids. The sod1 mutant was markedly attenuated in virulence in a mouse model, and it was significantly susceptible to in vitro killing by human neutrophils (PMNs). The deletion of SOD1 also resulted in defects in the expression of a number of virulence factors, i.e. laccase, urease and phospholipase. Complementation of the sod1 mutant with SOD1 resulted in recovery of virulence factor expression and menadione resistance, and in restoration of virulence. Overall, these results suggest that the antioxidant function of Cu,Zn SOD is critical for the pathogenesis of the fungus, but is dispensable in its saprobic life. This report constitutes the first instance in which superoxide dismutase has been directly implicated in the virulence of a fungal pathogen.