Song Tao, Tian Ying-Qi, Liu Chu-Bin, Gao Yi-Qun, Wang Ya-Ling, Zhang Jing, Su Yu, Xu Li-Na, Han Mei-Ling, Salt David E, Chao Dai-Yin
National Key Laboratory of Plant Molecular Genetics, Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.
University of Chinese Academy of Sciences, Beijing, China.
Nat Plants. 2023 Oct;9(10):1749-1759. doi: 10.1038/s41477-023-01503-z. Epub 2023 Aug 31.
Cell-cell junctions are essential for multicellular organisms to maintain nutrient homoeostasis. A plant-type tight junction, the Casparian strip (CS)-Casparian strip membrane domain (CSD) that seals the paracellular space between adjacent endodermal cells, has been known for more than one hundred years. However, the molecular basis of this structure remains unknown. Here we report that a new family of proteins containing a glycine/alanine/proline-rich domain, a lectin domain and a secretory signal peptide (GAPLESS) mediates tethering of the plasma membrane to the CS in rice. The GAPLESS proteins are specifically localized in the CS of root endodermal cells, and loss of their functions results in a disabled cell-cell junction and disrupted nutrient homoeostasis. The GAPLESS protein forms a tight complex with OsCASP1 in the plasma membrane, thereby mediating the CS-CSD junction. This study provides valuable insights into the junctional complex of plant endodermal cells, shedding light on our understanding of nutrient homoeostasis in crops and the cell junctions of eukaryotes.
细胞间连接对于多细胞生物维持营养稳态至关重要。一种植物型紧密连接，即凯氏带（CS）-凯氏带膜结构域（CSD），它封闭相邻内皮层细胞之间的细胞旁空间，已经被人们所知超过一百年了。然而，这种结构的分子基础仍然未知。在此我们报告，一个包含富含甘氨酸/丙氨酸/脯氨酸结构域、凝集素结构域和分泌信号肽的新蛋白质家族（GAPLESS）介导了水稻中质膜与凯氏带的连接。GAPLESS蛋白特异性定位于根内皮层细胞的凯氏带，其功能丧失会导致细胞间连接功能失调以及营养稳态被破坏。GAPLESS蛋白在质膜中与OsCASP1形成紧密复合物，从而介导凯氏带-凯氏带膜结构域连接。这项研究为植物内皮层细胞的连接复合物提供了有价值的见解，有助于我们理解作物中的营养稳态以及真核生物的细胞连接。
