title: The rice RING finger E3 ligase, OsHCI1, drives nuclear export of multiple substrate proteins and its heterogeneous overexpression enhances acquired thermotolerance.
abstract: Thermotolerance is very important for plant survival when plants are subjected to lethally high temperature. However, thus far little is known about the functions of RING E3 ligase in response to heat shock in plants. This study found that one rice gene encoding the RING finger protein was specifically induced by heat and cold stress treatments but not by salinity or dehydration and named it OsHCI1 (Oryza sativa heat and cold induced 1). Subcellular localization results showed that OsHCI1 was mainly associated with the Golgi apparatus and moved rapidly and extensively along the cytoskeleton. In contrast, OsHCI1 may have accumulated in the nucleus under high temperatures. OsHCI1 physically interacted with nuclear substrate proteins including a basic helix-loop-helix transcription factor. Transient co-overexpression of OsHCI1 and each of three nuclear proteins showed that their fluorescent signals moved into the cytoplasm as punctuate formations. Heterogeneous overexpression of OsHCI1 in Arabidopsis highly increased survival rate through acquired thermotolerance. It is proposed that OsHCI1 mediates nuclear-cytoplasmic trafficking of nuclear substrate proteins via monoubiquitination and drives an inactivation device for the nuclear proteins under heat shock.
authors.affiliation: Department of Applied Plant Sciences, Kangwon National University, Chuncheon 200-713, Korea.
authors.forename: Sung Don
authors.initials: SD
authors.lastname: Lim
authors.forename: Hyun Yong
authors.initials: HY
authors.lastname: Cho
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Park
authors.forename: Deok Jae
authors.initials: DJ
authors.lastname: Ham
authors.forename: Ju Kyong
authors.initials: JK
authors.lastname: Lee
authors.forename: Cheol Seong
authors.initials: CS
authors.lastname: Jang
mesh_terms: D021581:Active Transport, Cell Nucleus; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D006056:Golgi Apparatus / Q000201:enzymology / Q000235:genetics; D006358:Hot Temperature; D012275:Oryza / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D021381:Protein Transport; D054829:RING Finger Domains; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D044767:Ubiquitin-Protein Ligases
keywords: Abiotic stress; RING E3 ligase; cytoplasmic trafficking; monoubiquitination; nuclear–; rice; thermotolerance.