Fluorescence in blue light (FLU) is involved in inactivation and localization of glutamyl-tRNA reductase during light exposure
Fluorescence in blue light (FLU) is involved in inactivation and localization of glutamyl-tRNA reductase during light exposure
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DOI：
10.1111/tpj.14138
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发表时间：
2019-02-01
期刊：
影响因子：
7.2
通讯作者：
Grimm, Bernhard
中科院分区：
文献类型：
--
作者：
Hou, Zhiwei;Yang, Yanyu;Grimm, Bernhard
蓝光荧光（FLU）是一种负调控因子，参与5-氨基乙酰丙酸（ALA）合成的黑暗抑制，并与四吡咯生物合成的限速酶谷氨酰-tRNA还原酶（GluTR）相互作用。在这项研究中，我们研究了FLU的调节功能，在光暴露的FLUOE过表达（FLUOE）拟南芥线和波动的光强度下，在野生型（WT）和流感幼苗。FLUOE株系在光照下抑制ALA合成，导致叶绿素含量降低，但在低光和强光下比在中等生长光下更强烈。这种情况表明FLU对叶绿素生物合成的影响取决于光照强度。FLU过表达者含有大量增加的主要膜相关GluTR。这些发现与Glu TR到质体膜的FLU-dependent定位和伴随的抑制相关，使得仅可溶性Glu TR级分是活性的。膜相关GluTR的过度积累表明FLU结合增强GluTR稳定性。有趣的是，在波动的光照下，流感突变体的叶片与野生型相比含有更少的叶绿素，并变得坏死。我们建议，FLU基本上是需要微调ALA合成。FLU不仅介导ALA合成的暗抑制，而且还在可变光强度下控制ALA合成的平衡，以确保叶绿素的充足供应。
Fluorescent in blue light (FLU) is a negative regulator involved in dark repression of 5-aminolevulinic acid (ALA) synthesis and interacts with glutamyl-tRNA reductase (GluTR), the rate-limiting enzyme of tetrapyrrole biosynthesis. In this study, we investigated FLU's regulatory function in light-exposed FLU-overexpressing (FLUOE) Arabidopsis lines and under fluctuating light intensities in wild-type (WT) and flu seedlings. FLUOE lines suppress ALA synthesis in the light, resulting in reduced chlorophyll content, but more strongly in low and high light than in medium growth light. This situation indicates that FLU's impact on chlorophyll biosynthesis depends on light intensity. FLU overexpressors contain strongly increased amounts of mainly membrane-associated GluTR. These findings correlate with FLU-dependent localization of GluTR to plastidic membranes and concomitant inhibition, such that only the soluble GluTR fraction is active. The overaccumulation of membrane-associated GluTR indicates that FLU binding enhances GluTR stability. Interestingly, under fluctuating light, the leaves of flu mutants contain less chlorophyll compared with WT and become necrotic. We propose that FLU is basically required for fine-tuned ALA synthesis. FLU not only mediates dark repression of ALA synthesis, but functions also to control balanced ALA synthesis under variable light intensities to ensure the adequate supply of chlorophyll.