Post-Golgi trafficking of rice storage proteins requires the small GTPase Rab7 activation complex MON1–CCZ1

• DOI: 10.1093/plphys/kiab175
• Publication Date: 2021-04-16T19:14:39Z
• Authors: Tian Pan; Yihua Wang; Ruonan Jing; Yongfei Wang; Zhongyan Wei; Binglei Zhang; Cailin Lei; Yanzhou Qi; Fan Wang; Xiuhao Bao; Mengyuan Yan; Yu Zhang; Pengcheng Zhang; Mingzhou Yu; Gexing Wan; Yu Chen; Wenkun Yang; Jianping Zhu; Yun Zhu; Shanshan Zhu; Zhijun Cheng; Xin Zhang; Ling Jiang; Yulong Ren; Jianmin Wan
• Keywords: Glutelin; Rab; Transport protein

Protein storage vacuoles (PSVs) are unique organelles that accumulate proteins in plant seeds. Although morphological evidence points to the existence of multiple PSV-trafficking pathways for protein targeting, molecular mechanisms regulate these processes remain mostly unknown. Here, we report functional characterization rice (Oryza sativa) glutelin precursor accumulation7 (gpa7) mutant, which over-accumulates 57-kDa precursors dry Cytological and immunocytochemistry studies revealed gpa7 mutant exhibits abnormal accumulation prevacuolar compartment-like structures, accompanied by partial mistargeting glutelins extracellular space. The was altered CCZ1 locus, encodes homolog Arabidopsis (Arabidopsis thaliana) CALCIUM CAFFEINE ZINC SENSITIVITY1a (CCZ1a) CCZ1b. Biochemical showed interacts with MONENSIN SENSITIVITY1 (MON1) function together as Rat brain 5 (Rab5) effector Rab7 guanine nucleotide exchange factor (GEF). Notably, loss promoted endosomal localization vacuolar sorting-associated 9 (VPS9), is GEF Rab5 plants. Together, our results indicate MON1-CCZ1 complex involved post-Golgi trafficking through a Rab5- Rab7-dependent pathway.