A plant Bro1 domain protein BRAF regulates multivesicular body biogenesis and membrane protein homeostasis

• Published in: Nature communications Vol. 9; no. 1; pp. 3784 - 15
• Main Authors: Shen, Jinbo, Zhao, Qiong, Wang, Xiangfeng, Gao, Caiji, Zhu, Ying, Zeng, Yonglun, Jiang, Liwen
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.09.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 14/1; 14/19; 14/28; 38/109; 38/35; 38/77; 45/70; 631/449/448/2024; 631/80/313/2162; 82/29; 82/80; 82/83; Arabidopsis - cytology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Binding, Competitive; Biosynthesis; Carrier Proteins - genetics; Carrier Proteins - metabolism; Degradation; Endosomal Sorting Complexes Required for Transport - metabolism; Eukaryotes; Homeostasis; Humanities and Social Sciences; Industrial plants; Intracellular Membranes - metabolism; Membrane proteins; multidisciplinary; Multivesicular Bodies - metabolism; Mutation; Plant Cells - metabolism; Plants, Genetically Modified; Protein Domains; Proteins; Proteostasis; Regulators; Regulatory mechanisms (biology); RNA Interference; Science; Science (multidisciplinary); Vacuoles - metabolism; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - metabolism
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-05913-y

Plant development, defense, and many physiological processes rely on the endosomal sorting complex required for transport (ESCRT) machinery to control the homeostasis of membrane proteins by selective vacuolar degradation. Although ESCRT core components are conserved among higher eukaryotes, the regulators that control the function of the ESCRT machinery remain elusive. We recently identified a plant-specific ESCRT component, FREE1, that is essential for multivesicular body/prevacuolar compartment (MVB/PVC) biogenesis and vacuolar sorting of membrane proteins. Here we identify a plant-specific Bro1-domain protein BRAF, which regulates FREE1 recruitment to the MVB/PVC membrane by competitively binding to the ESCRT-I component Vps23. Altogether, we have successfully identified a role for BRAF, whose function as a unique evolutionary ESCRT regulator in orchestrating intraluminal vesicle formation in MVB/PVCs and the sorting of membrane proteins for degradation in plants makes it an important regulatory mechanism underlying the ESCRT machinery in higher eukaryotes. The ESCRT complex contributes to selective vacuolar degradation of membrane proteins. Here, the authors show that the plant-specific BRAF protein negatively regulates intraluminal vesicle formation and membrane protein degradation by preventing FREE1 binding to the ESCRT-I complex protein Vps23.