N-Terminus-Mediated Degradation of ACS7 Is Negatively Regulated by Senescence Signaling to Allow Optimal Ethylene Production during Leaf Development in Arabidopsis.
N-Terminus-Mediated Degradation of ACS7 Is Negatively Regulated by Senescence Signaling to Allow Optimal Ethylene Production during Leaf Development in Arabidopsis.
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ACS7 N 端介导的降解受到衰老信号的负调控，以在拟南芥叶片发育过程中实现最佳乙烯生产
DOI：
10.3389/fpls.2017.02066
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发表时间：
2017
影响因子：
5.6
通讯作者：
Wang NN
中科院分区：
文献类型：
--
作者：
Sun G;Mei Y;Deng D;Xiong L;Sun L;Zhang X;Wen Z;Liu S;You X;Nasrullah;Wang D;Wang NN
衰老是叶片发育的最后阶段，其特征在于被困在退化叶片中的资源被降解和再循环以维持新形成的器官的生长的关键过程。由于气体激素乙烯对叶片衰老的进程产生深远的影响，其生物合成的最佳时间和量对于控制叶片发育至关重要。在高等植物中控制乙烯合成的限速酶是ACC合成酶（ACS）。在这项研究中，我们评估了乙烯的生产，并揭示了在拟南芥叶片衰老过程中的ACS 7的上调。我们进一步表明，ACS 7的启动子活性在整个莲座发育过程中保持在相对较高的水平。而在光照条件下，幼苗中ACS 7蛋白的积累水平极低，随着植株的衰老逐渐恢复。我们以前证明，ACS 7的降解是由其前14个N-末端残基，在这里，我们比较了表型的转基因拟南芥过表达的截短的ACS 7缺乏14个残基与转基因植物过表达全长蛋白。结果表明，过表达截短的ACS 7的幼苗表现出衰老表型比过表达全长基因的幼苗早得多。融合的14个残基的SSPP，PP 2C型衰老抑制蛋白磷酸酶，有效地挽救了SSPP诱导的抑制莲座生长和发育，但对延迟衰老没有影响。这一观察结果进一步支持了N-末端介导的ACS 7降解受叶片衰老信号传导负调控。因此，本研究的所有结果表明，ACS 7是合成“衰老乙烯”的主要贡献者之一。更重要的是，N-末端14个残基介导的这种蛋白质的降解受到衰老信号的高度调节，使植物能够产生所需的适当水平的乙烯。
Senescence is the final phase of leaf development, characterized by key processes by which resources trapped in deteriorating leaves are degraded and recycled to sustain the growth of newly formed organs. As the gaseous hormone ethylene exerts a profound effect on the progression of leaf senescence, both the optimal timing and amount of its biosynthesis are essential for controlled leaf development. The rate-limiting enzyme that controls ethylene synthesis in higher plants is ACC synthase (ACS). In this study, we evaluated the production of ethylene and revealed an up-regulation of ACS7 during leaf senescence in Arabidopsis. We further showed that the promoter activity of ACS7 was maintained at a relatively high level throughout the whole rosette development process. However, the accumulation level of ACS7 protein was extremely low in the light-grown young seedlings, and it was gradually restored as plants aging. We previously demonstrated that degradation of ACS7 is regulated by its first 14 N-terminal residues, here we compared the phenotypes of transgenic Arabidopsis overexpressing a truncated ACS7 lacking the 14 residues with transgenic plants overexpressing the full-length protein. Results showed that seedlings overexpressing the truncated ACS7 exhibited a senescence phenotype much earlier than their counterparts overexpressing the full-length gene. Fusion of the 14 residues to SSPP, a PP2C-type senescence-suppressed protein phosphatase, effectively rescued the SSPP-induced suppression of rosette growth and development but had no effect on the delayed senescence. This observation further supported that N-terminus-mediated degradation of ACS7 is negatively regulated by leaf senescence signaling. All results of this study therefore suggest that ACS7 is one of the major contributors to the synthesis of ‘senescence ethylene’. And more importantly, the N-terminal 14 residue-mediated degradation of this protein is highly regulated by senescence signaling to enable plants to produce the appropriate levels of ethylene required.
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影响因子：
7.2
作者：
Morita, Ryouhei;Sato, Yutaka;Kusaba, Makoto
通讯作者：
Kusaba, Makoto
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF
影响因子：
7.2
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Lyzenga, Wendy J.;Booth, Judith K.;Stone, Sophia L.
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Stone, Sophia L.
影响因子：
6.9
作者：
Jing, HC;Schippers, JHM;Dijkwei, PP
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Dijkwei, PP
影响因子：
6.4
作者：
LOHMAN, KN;GAN, SS;AMASINO, RM
通讯作者：
AMASINO, RM