A possible CO2 conducting and concentrating mechanism in plant stomata SLAC1 channel.
A possible CO2 conducting and concentrating mechanism in plant stomata SLAC1 channel.
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植物气孔SLAC1通道中可能的CO2传导和浓缩机制。
DOI：
10.1371/journal.pone.0024264
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Huang RB
中科院分区：
文献类型：
--
作者：
Du QS;Fan XW;Wang CH;Huang RB
植物SLAC 1是气孔保卫细胞膜上的一个慢阴离子通道，它控制着气孔保卫细胞的膨压，从而调节水蒸气和光合气体的交换，以响应环境信号，如干旱、高水平的二氧化碳和细菌入侵。最近的研究表明，碳酸氢盐是SLAC 1的小分子激活剂。较高的CO2和HCO 3浓度激活野生型拟南芥保卫细胞的S型阴离子通道电流。基于SLAC 1的结构，推导出一个理论模型来说明碳酸氢根对SLAC 1通道的激活。同时提出了SLAC 1可能的CO2传导和浓缩机理。拟南芥SLAC 1（AtSLAC 1）的同源结构为研究SLAC 1通道中二氧化碳的传导和浓缩机制提供了结构基础。利用PROPKA3.0软件计算了AtSLAC 1中可电离氨基酸侧链的pKa值，并根据化学平衡理论计算了CO2和HCO 3-的浓度。AtSLAC 1被建模为具有不同pH值的五区域通道。通道的上下两层为碱性残基为主的区域，通道中部为酸性残基His 332周围的酸性区域。由于这些区域之间的pH差异，CO2浓度增加了约104倍，并且CO2储存在疏水区域中，这是CO2库。pH驱动的CO2从外到内的传导平衡了反电动势，并保持阴离子（例如Cl-和NO3 -）从内到外的流入。SLAC 1可能是保卫细胞光合作用的CO2提供途径。
The plant SLAC1 is a slow anion channel in the membrane of stomatal guard cells, which controls the turgor pressure in the aperture-defining guard cells, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought, high levels of carbon dioxide, and bacterial invasion. Recent study demonstrated that bicarbonate is a small-molecule activator of SLAC1. Higher CO2 and HCO3 – concentration activates S-type anion channel currents in wild-type Arabidopsis guard cells. Based on the SLAC1 structure a theoretical model is derived to illustrate the activation of bicarbonate to SLAC1 channel. Meanwhile a possible CO2 conducting and concentrating mechanism of the SLAC1 is proposed. The homology structure of Arabidopsis thaliana SLAC1 (AtSLAC1) provides the structural basis for study of the conducting and concentrating mechanism of carbon dioxide in SLAC1 channels. The pKa values of ionizable amino acid side chains in AtSLAC1 are calculated using software PROPKA3.0, and the concentration of CO2 and anion HCO3 – are computed based on the chemical equilibrium theory. The AtSLAC1 is modeled as a five-region channel with different pH values. The top and bottom layers of channel are the alkaline residue-dominated regions, and in the middle of channel there is the acidic region surrounding acidic residues His332. The CO2 concentration is enhanced around 104 times by the pH difference between these regions, and CO2 is stored in the hydrophobic region, which is a CO2 pool. The pH driven CO2 conduction from outside to inside balances the back electromotive force and maintain the influx of anions (e.g. Cl– and NO3 –) from inside to outside. SLAC1 may be a pathway providing CO2 for photosynthesis in the guard cells.
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影响因子：
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DOI：
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