Distinct roles of two cytoplasmic thioredoxin reductases (Trr1/2) in the redox system involving cysteine synthesis and host infection of Beauveria bassiana
Distinct roles of two cytoplasmic thioredoxin reductases (Trr1/2) in the redox system involving cysteine synthesis and host infection of Beauveria bassiana
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DOI：
10.1007/s00253-016-7688-0
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发表时间：
2016-06
影响因子：
5
通讯作者：
Long-Bin Zhang;Li Tang;S. Ying;M. Feng
中科院分区：
文献类型：
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作者：
Long-Bin Zhang;Li Tang;S. Ying;M. Feng
已知两种硫氧还蛋白 (Trx) 还原酶 (Trr1/2) 在酵母 Trx-Trr 氧化还原系统中发挥重叠作用，但在丝状真菌中通常未被探索，丝状真菌具有多个 Trx 同源物。本研究旨在表征白僵菌（一种丝状真菌昆虫病原体）中 Trr1 和 Trr2 的功能，并探讨它们的 Trx 伙伴。 Trr1 和 Trr2 均明显定位于白僵菌的细胞质中，这与已报道的分别定位于细胞质和线粒体中的两种酵母同源物不同。在白僵菌中，在trr1而不是trr2缺失的情况下，大多数sixtrx基因在转录水平上大幅上调，其中trr1/2双缺失多次尝试均失败。删除trr1会导致Trx活性增加、严重的半胱氨酸营养缺陷型以及在正常或氧化条件下过氧化物酶和超氧化物歧化酶的活性急剧降低，尽管过氧化氢酶活性几乎没有变化。这种变化在trr2不存在的情况下消失，并通过Δtrr1突变体中trr1/2的互补或trx1/6的过度表达而完全恢复，但在同一突变体中trx2/3/4/5或trr2的过度表达根本不能恢复。所有这些突变体在抗氧化反应、分生孢子形成、发芽、耐热性、UV-B 抗性和毒力方面都表现出相似的变化趋势。综上所述，研究结果表明，Trr1 可以减少 Trx2-5，从而主导细胞内氧化还原状态，深刻影响白僵菌对抗节肢动物害虫的潜力。 Trr2 可以减少 Trx1/6，但仅在没有 Trr1 的情况下发挥作用。
Two thioredoxin (Trx) reductases (Trr1/2) are known to play overlapping roles in the yeast Trx-Trr redox system but are generally unexplored in filamentous fungi, which possess multiple Trx homologues. This study seeks to characterize the functions of Trr1 and Trr2 inBeauveria bassiana, a filamentous fungal insect pathogen, and to probe their Trx partners. Both Trr1 and Trr2 were evidently localized in the cytoplasm ofB.bassiana, unlike the two yeast homologues that have been reported to localize in the cytoplasm and mitochondria, respectively. Most of the sixtrxgenes were greatly upregulated at the transcriptional level in the absence oftrr1instead oftrr2inB.bassiana, in which thetrr1/2double deletion failed in many attempts. Deletion oftrr1resulted in increased Trx activity, severe cysteine auxotrophy, and drastically reduced activities of peroxidases and superoxide dismutases under normal or oxidative conditions despite little change in catalase activity. Such changes disappeared in the absence oftrr2and were completely restored by complementation oftrr1/2or overexpression oftrx1/6in the Δtrr1mutant, but were not restored at all by overexpression oftrx2/3/4/5ortrr2in the same mutant. All of these mutants exhibited similar trends of changes in the antioxidant response, conidiation, germination, thermotolerance, UV-B resistance, and virulence. Taken together, the findings indicate that Trr1 could reduce Trx2–5 and hence dominate the intracellular redox state, profoundly affecting the potential ofB.bassianaagainst arthropod pests. Trr2 could reduce Trx1/6 but function only in the absence of Trr1.