Department of Biological Sciences, Konkuk University, Seoul, 05029, South Korea.
Department of Molecular Biology, Dankook University, Cheonan, 31116, South Korea.
Biochem Biophys Res Commun. 2020 Apr 16;524(4):977-982. doi: 10.1016/j.bbrc.2020.02.029. Epub 2020 Feb 12.
We previously found that VAMP721/722 SNARE proteins guide secretory vesicles to pathogen-attacking sites during immune responses in Arabidopsis, which suggests that these vesicles should deliver immune molecules. However, the lethality of vamp721 vamp722 double null mutant makes it difficult to understand the nature of cargo transported via VAMP721/722 vesicles. Since VAMP721/722-depleted (VAMP721VAMP722 and VAMP721VAMP722) plants show compromised resistance to extracellular pathogens, we assume that an immune protein secreted through the VAMP721/722-engaged exocytosis would be remained more in VAMP721/722-depleted plants than WT. By comparing intracellular proteins between WT and VAMP721/722-depleted plants, we found caffeoyl-CoA O-methyltransferase 1 (CCOAOMT1) involved in the lignin biosynthesis was more abundantly detected in both VAMP721/722-depleted lines than WT. Plants are well-known to deposit secondary cell walls as physical barriers at pathogen-attempting sites. Therefore, extracellular detection of CCOAOMT1 and impaired resistance to Pseudomonas syringae DC3000 in ccoaomt1 plants suggest that plants secrete cell wall-modifying enzymes at least including CCOAOMT1 to reinforce the secondary cell walls for immunity.
我们之前发现 VAMP721/722 SNARE 蛋白在拟南芥的免疫反应中引导分泌囊泡到病原体攻击部位，这表明这些囊泡应该输送免疫分子。然而，vamp721 vamp722 双突变体的致死性使得很难理解通过 VAMP721/722 囊泡运输的货物的性质。由于 VAMP721/722 耗尽（VAMP721VAMP722 和 VAMP721VAMP722）的植物对细胞外病原体的抗性降低，我们假设通过 VAMP721/722 参与的胞吐作用分泌的免疫蛋白在 VAMP721/722 耗尽的植物中比 WT 中更易保留。通过比较 WT 和 VAMP721/722 耗尽植物之间的细胞内蛋白，我们发现参与木质素生物合成的咖啡酰辅酶 A O-甲基转移酶 1（CCOAOMT1）在两种 VAMP721/722 耗尽系中比 WT 中更丰富。众所周知，植物在病原体试图进入的部位沉积次生细胞壁作为物理屏障。因此，CCOAOMT1 的细胞外检测和 ccoaomt1 植物对丁香假单胞菌 DC3000 的抗性受损表明，植物至少分泌细胞壁修饰酶，包括 CCOAOMT1，以增强次生细胞壁的免疫功能。
