Ascorbate peroxidase 4 plays a role in the tolerance of Chlamydomonas reinhardtii to photo-oxidative stress
Ascorbate peroxidase 4 plays a role in the tolerance of Chlamydomonas reinhardtii to photo-oxidative stress
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DOI：
10.1038/s41598-020-70247-z
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发表时间：
2020-08-06
影响因子：
4.6
通讯作者：
Lee, Tse-Min
中科院分区：
文献类型：
--
作者：
Kuo, Eva YuHua;Cai, Meng-Siou;Lee, Tse-Min
在1400亩E.M(-2)·s(-1)条件下，莱茵衣藻的抗坏血酸过氧化物酶(APX；EC 1.11.1.11)活性和CrAPX1、CrAPX2和CrAPX4的转录水平增加。其中以CrAPX4的表达最为显著。因此，利用amiRNA技术下调了CrAPX4的表达，以检测APX在HL驯化中的作用。CrAPX4基因敲除的amiRNA系表现出较低的APX活性和CrAPX4转录水平，而CrAPX1和CrAPX2的转录水平没有变化，而单脱氢抗坏血酸还原酶(MDAR)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)的活性和转录水平没有变化。在HL作用下，CrAPX4基因敲除的AMIRNA细胞的抗坏血酸-谷胱甘肽循环中的酶基因表达发生改变，包括抗坏血酸(ASA)生物合成关键酶CrVTC2的转录水平增加，但1h后MDAR和DHAR的转录和活性降低，6h后活性氧产生和脂质过氧化增加，9h后细胞死亡。因此，CrAPX4的诱导及其与MDAR和DHAR表达的调节对于衣藻应对光氧化胁迫是至关重要的。
Ascorbate peroxidase (APX; EC 1.11.1.11) activity and transcript levels of CrAPX1, CrAPX2, and CrAPX4 of Chlamydomonas reinhardtii increased under 1,400 mu E.m(-2).s(-1) condition (HL). CrAPX4 expression was the most significant. So, CrAPX4 was downregulated using amiRNA technology to examine the role of APX for HL acclimation. The CrAPX4 knockdown amiRNA lines showed low APX activity and CrAPX4 transcript level without a change in CrAPX1 and CrAPX2 transcript levels, and monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) activities and transcript levels. Upon exposure to HL, CrAPX4 knockdown amiRNA lines appeared a modification in the expression of genes encoding the enzymes in the ascorbate-glutathione cycle, including an increase in transcript level of CrVTC2, a key enzyme for ascorbate (AsA) biosynthesis but a decrease in MDAR and DHAR transcription and activity after 1 h, followed by increases in reactive oxygen species production and lipid peroxidation after 6 h and exhibited cell death after 9 h. Besides, AsA content and AsA/DHA (dehydroascorbate) ratio decreased in CrAPX4 knockdown amiRNA lines after prolonged HL treatment. Thus, CrAPX4 induction together with its association with the modulation of MDAR and DHAR expression for AsA regeneration is critical for Chlamydomonas to cope with photo-oxidative stress.