title: Arabidopsis LIP5, a positive regulator of multivesicular body biogenesis, is a critical target of pathogen-responsive MAPK cascade in plant basal defense.
abstract: Multivesicular bodies (MVBs) play essential roles in many cellular processes. The MVB pathway requires reversible membrane association of the endosomal sorting complexes required for transports (ESCRTs) for sustained protein trafficking. Membrane dissociation of ESCRTs is catalyzed by the AAA ATPase SKD1, which is stimulated by LYST-interacting protein 5 (LIP5). We report here that LIP5 is a target of pathogen-responsive mitogen-activated protein kinases (MPKs) and plays a critical role in plant basal resistance. Arabidopsis LIP5 interacts with MPK6 and MPK3 and is phosphorylated in vitro by activated MPK3 and MPK6 and in vivo upon expression of MPK3/6-activating NtMEK2DD and pathogen infection. Disruption of LIP5 has little effects on flg22-, salicylic acid-induced defense responses but compromises basal resistance to Pseudomonas syringae. The critical role of LIP5 in plant basal resistance is dependent on its ability to interact with SKD1. Mutation of MPK phosphorylation sites in LIP5 does not affect interaction with SKD1 but reduces the stability and compromises the ability to complement the lip5 mutant phenotypes. Using the membrane-selective FM1-43 dye and transmission electron microscopy, we demonstrated that pathogen infection increases formation of both intracellular MVBs and exosome-like paramural vesicles situated between the plasma membrane and the cell wall in a largely LIP5-dependent manner. These results indicate that the MVB pathway is positively regulated by pathogen-responsive MPK3/6 through LIP5 phosphorylation and plays a critical role in plant immune system likely through relocalization of defense-related molecules.
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou, China.
authors.forename: Yifen
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Baofang
authors.initials: B
authors.lastname: Fan
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou, China.
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America; Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou, China.
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Chen
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology*; D020935:MAP Kinase Signaling System / Q000235:genetics / Q000276:immunology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000276:immunology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000276:immunology; D009154:Mutation; D010935:Plant Diseases / Q000382:microbiology*; D057865:Plant Immunity / Q000502:physiology*; D044224:Pseudomonas syringae / Q000235:genetics / Q000276:immunology*
chemical_list: D029681:Arabidopsis Proteins; C458516:AtMPK3 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases