title: Molecular dissection of a rice microtubule-associated RING finger protein and its potential role in salt tolerance in Arabidopsis.
abstract: Although a number of RING E3 ligases in plants have been demonstrated to play key roles in a wide range of abiotic stresses, relatively few studies have detailed how RING E3 ligases exert their cellular actions. We describe Oryza sativa RING finger protein with microtubule-targeting domain 1 (OsRMT1), a functional RING E3 ligase that is likely involved in a salt tolerance mechanism. Functional characterization revealed that OsRMT1 undergoes homodimer formation and subsequently autoubiquitination-mediated protein degradation under normal conditions. By contrast, OsRMT1 is predominantly found in the nucleus and microtubules and its degradation is inhibited under salt stress. Domain dissection of OsRMT1 indicates that the N-terminal domain is required for microtubule targeting. Bimolecular fluorescence complementation analysis and degradation assay revealed that OsRMT1-interacted proteins localized in various organelles were degraded via the ubiquitin (Ub)/26S proteasome-dependent pathway. Interestingly, when OsRMT1 and its target proteins were co-expressed in N. benthamiana leaves, the protein-protein interactions appeared to take place mainly in the microtubules. Overexpression of OsRMT1 in Arabidopsis resulted in increased tolerance to salt stress. Our findings suggest that the abundance of microtubule-associated OsRMT1 is strictly regulated, and OsRMT1 may play a relevant role in salt stress response by modulating levels of its target proteins.
authors.affiliation: Department of Applied Plant Sciences Technology, Kangwon National University, Chuncheon, 200-713, Korea.
authors.forename: Sung Don
authors.initials: SD
authors.lastname: Lim
authors.affiliation: Department of Applied Plant Sciences Technology, Kangwon National University, Chuncheon, 200-713, Korea.
authors.forename: Chang Gyo
authors.initials: CG
authors.lastname: Jung
authors.affiliation: Department of Applied Plant Sciences Technology, Kangwon National University, Chuncheon, 200-713, Korea.
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Park
authors.affiliation: School of Biological Sciences, Chung-Ang University, Seoul, 156-756, Korea.
authors.forename: Sung Chul
authors.initials: SC
authors.lastname: Lee
authors.affiliation: Department of Plant Environmental New Resources, KyungHee University, Yongin, 446-701, Korea.
authors.forename: Chanhui
authors.initials: C
authors.lastname: Lee
authors.affiliation: School of Biological Sciences, Chung-Ang University, Seoul, 156-756, Korea.
authors.forename: Chae Woo
authors.initials: CW
authors.lastname: Lim
authors.affiliation: Adanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup, 580-185, Korea.
authors.forename: Dong Sub
authors.initials: DS
authors.lastname: Kim
authors.affiliation: Department of Applied Plant Sciences Technology, Kangwon National University, Chuncheon, 200-713, Korea. csjang@kangwon.ac.kr.
authors.forename: Cheol Seong
authors.initials: CS
authors.lastname: Jang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D017343:Genes, Plant; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D055503:Protein Multimerization; D054829:RING Finger Domains / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease
keywords: Microtubules; RING E3 ligase; Rice; Salt stress; Ubiquitination