Department of Biology, University of Padua, viale Giuseppe Colombo 3, 35121 Padua, Italy.
Science. 2013 Oct 4;342(6154):114-8. doi: 10.1126/science.1242113. Epub 2013 Sep 5.
The size of the light-induced proton motive force (pmf) across the thylakoid membrane of chloroplasts is regulated in response to environmental stimuli. Here, we describe a component of the thylakoid membrane, the two-pore potassium (K(+)) channel TPK3, which modulates the composition of the pmf through ion counterbalancing. Recombinant TPK3 exhibited potassium-selective channel activity sensitive to Ca(2+) and H(+). In Arabidopsis plants, the channel is found in the thylakoid stromal lamellae. Arabidopsis plants silenced for the TPK3 gene display reduced growth and altered thylakoid membrane organization. This phenotype reflects an impaired capacity to generate a normal pmf, which results in reduced CO2 assimilation and deficient nonphotochemical dissipation of excess absorbed light. Thus, the TPK3 channel manages the pmf necessary to convert photochemical energy into physiological functions.
叶绿体类囊体膜上光诱导的质子动力势（pmf）的大小受环境刺激的调节。在这里，我们描述了类囊体膜的一个组成部分，即双孔钾（K(+))通道 TPK3，它通过离子平衡来调节 pmf 的组成。重组 TPK3 表现出对 Ca(2+)和 H(+)敏感的钾选择性通道活性。在拟南芥植物中，该通道存在于类囊体基质片层中。沉默 TPK3 基因的拟南芥植物表现出生长缓慢和类囊体膜组织改变的表型。这种表型反映了生成正常 pmf 的能力受损，导致 CO2 同化减少和过量吸收光的非光化学耗散不足。因此，TPK3 通道管理将光化学能量转化为生理功能所需的 pmf。
