Feedback inhibition of AMT1 NH(4)(+)-transporters mediated by CIPK15 kinase.
Feedback inhibition of AMT1 NH(4)(+)-transporters mediated by CIPK15 kinase.
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DOI：
10.1186/s12915-020-00934-w
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发表时间：
2020-12-14
期刊：
影响因子：
5.4
通讯作者：
Ho CH
中科院分区：
文献类型：
--
作者：
Chen HY;Chen YN;Wang HY;Liu ZT;Frommer WB;Ho CH
铵（NH 4+）是一种关键的氮形式，当它积累到高水平时就会变得有毒。铵转运蛋白（AMTs）是负责NH 4+吸收的关键转运蛋白。AMT活性受变构反馈控制，由胞质C-末端（CCT）中苏氨酸的磷酸化介导。然而，负责NH 4+触发磷酸化的激酶仍然未知。在这项研究中，功能筛选确定蛋白激酶CBL相互作用蛋白激酶15（CIPK 15）作为AMT 1;1活性的负调节剂。CIPK 15能够在质膜上与几种AMT 1旁系同源物相互作用。对AmTryoshka（酵母中AMT 1;3的NH 4+转运体活性传感器）和非洲爪蟾卵母细胞中AMT 1;1的双电极电压钳（TEVC）的分析表明，CIPK 15抑制AMT活性。当幼苗暴露于升高的NH 4+水平时，CIPK 15转录水平增加。值得注意的是，与野生型相比，cipk 15敲除突变体显示出更高的15 NH 4+摄取和积累更高量的NH 4+。因此，cipk 15对NH 4+和甲基铵都很敏感，但对硝酸盐（NO3-）不敏感。综上所述，我们的数据表明，AMT 1活性的反馈抑制是由蛋白激酶CIPK 15介导的，通过磷酸化CCT中的残基来减少NH 4+积累。在线版本包含补充材料，可通过10.1186/s12915-020-00934-w获得。
Ammonium (NH4+), a key nitrogen form, becomes toxic when it accumulates to high levels. Ammonium transporters (AMTs) are the key transporters responsible for NH4+ uptake. AMT activity is under allosteric feedback control, mediated by phosphorylation of a threonine in the cytosolic C-terminus (CCT). However, the kinases responsible for the NH4+-triggered phosphorylation remain unknown. In this study, a functional screen identified protein kinase CBL-Interacting Protein Kinase15 (CIPK15) as a negative regulator of AMT1;1 activity. CIPK15 was able to interact with several AMT1 paralogs at the plasma membrane. Analysis of AmTryoshka, an NH4+ transporter activity sensor for AMT1;3 in yeast, and a two-electrode-voltage-clamp (TEVC) of AMT1;1 in Xenopus oocytes showed that CIPK15 inhibits AMT activity. CIPK15 transcript levels increased when seedlings were exposed to elevated NH4+ levels. Notably, cipk15 knockout mutants showed higher 15NH4+ uptake and accumulated higher amounts of NH4+ compared to the wild-type. Consistently, cipk15 was hypersensitive to both NH4+ and methylammonium but not nitrate (NO3−). Taken together, our data indicate that feedback inhibition of AMT1 activity is mediated by the protein kinase CIPK15 via phosphorylation of residues in the CCT to reduce NH4+-accumulation. The online version contains supplementary material available at 10.1186/s12915-020-00934-w.
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影响因子：
4
作者：
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影响因子：
4.5
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通讯作者：
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影响因子：
64.8
作者：
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通讯作者：
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