CrABCA2 Facilitates Triacylglycerol Accumulation in Chlamydomonas reinhardtii under Nitrogen Starvation
CrABCA2 Facilitates Triacylglycerol Accumulation in Chlamydomonas reinhardtii under Nitrogen Starvation
复制标题
CrABCA2 促进氮饥饿下莱茵衣藻三酰甘油的积累
DOI：
10.14348/molcells.2019.0262
复制
发表时间：
2020-01-01
影响因子：
3.8
通讯作者：
Lee, Youngsook
中科院分区：
文献类型：
--
作者：
Jang, Sunghoon;Kong, Fantao;Lee, Youngsook
在压力条件下，如氮饥饿，莱茵衣藻在脂滴中积累三酰甘油（TAG）。TAG生物合成主要发生在内质网（ER），并且需要由叶绿体提供的脂肪酸（FA）底物。在微藻中，脂肪酸是如何从叶绿体转移到内质网的尚不清楚。我们以前报道，拟南芥ATP结合盒（ABC）转运蛋白，AtABCA9，促进FA在种子发育过程中的ER运输。我们在C. reinhardtii基因组，我们将其命名为CrABCA 2。在氮剥夺条件下，CrABCA 2表达上调，CrABCA 2蛋白水平也增加。CrABCA 2敲除系积累较少的TAG，CrABCA 2过表达系积累更多的TAG比其未转化的亲本系。透射电子显微镜显示CrABCA 2定位于肿胀的ER中。这些结果表明，CrABCA 2运输底物TAG生物合成的ER在氮饥饿。我们的研究为增加微藻中的脂质产量提供了潜在的工具。
The microalga Chlamydomonas reinhardtii accumulates triacylglycerols ( TAGs) in lipid droplets under stress conditions, such as nitrogen starvation. TAG biosynthesis occurs mainly at the endoplasmic reticulum (ER) and requires fatty acid (FA) substrates supplied from chloroplasts. How FAs are transferred from chloroplast to ER in microalgae was unknown. We previously reported that an Arabidopsis thaliana ATP-binding cassette (ABC) transporter, AtABCA9, facilitates FA transport at the ER during seed development. Here we identified a gene homologous to AtABCA9 in the C. reinhardtii genome, which we named CrABCA2. Under nitrogen deprivation conditions, CrABCA2 expression was upregulated, and the CrABCA2 protein level also increased. CrABCA2 knockdown lines accumulated less TAGs and CrABCA2 overexpression lines accumulated more TAGs than their untransformed parental lines. Transmission electron microscopy showed that CrABCA2 was localized in swollen ER. These results suggest that CrABCA2 transports substrates for TAG biosynthesis to the ER during nitrogen starvation. Our study provides a potential tool for increasing lipid production in microalgae.