The MtDMI2-MtPUB2 Negative Feedback Loop Plays a Role in Nodulation Homeostasis.

摘要: DOES NOT MAKE INFECTION 2 (MtDMI2) is a Leu rich repeat-type receptor kinase required for signal transduction in the Medicago truncatula/Sinorhizobium meliloti symbiosis pathway. However, mechanisms through which MtDMI2 participates nodulation homeostasis are poorly understood. In this study, we identified MtPUB2-a novel plant U-box (PUB)-type E3 ligase-and showed that it interacts with MtDMI2. and MtPUB2 accumulation were shown to be similar various tissues. Roots of plants was silenced by RNAi (MtPUB2-RNAi plants) exhibited impaired infection threads, fewer nodules, shorter primary root lengths compared those control transformed empty vector. Using liquid chromatography-tandem mass spectrometry, phosphorylates at Ser-316, Ser-421, Thr-488 residues. When MtPUB2-RNAi MtPUB2S421D , mimics phosphorylated state, persistently ubiquitinated degraded MtPUB2S421D, resulting nodules than observed MtPUB2/MtPUB2-RNAi-complemented plants. MtPUB2S421A /MtPUB2-RNAi-complemented no ubiquitination activity, their phenotype Further studies demonstrated these proteins form negative feedback loop prey (MtDMI2)-predator (MtPUB2) type. Our results suggest MtDMI2-MtPUB2 loop, displays crosstalk long-distance autoregulation via MtNIN, plays an important role homeostasis.