title: Involvement of the Arabidopsis HIT1/AtVPS53 tethering protein homologue in the acclimation of the plasma membrane to heat stress.
abstract: Arabidopsis thaliana hit1-1 is a heat-intolerant mutant. The HIT1 gene encodes a protein that is homologous to yeast Vps53p, which is a subunit of the Golgi-associated retrograde protein (GARP) complex that is involved in retrograde membrane trafficking to the Golgi. To investigate the correlation between the cellular role of HIT1 and its protective function in heat tolerance in plants, it was verified that HIT1 was co-localized with AtVPS52 and AtVPS54, the other putative subunits of GARP, in the Golgi and post-Golgi compartments in Arabidopsis protoplasts. A bimolecular fluorescence complementation assay showed that HIT1 interacted with AtVPS52 and AtVPS54, which indicated their assembly into a protein complex in vivo. Under heat stress conditions, the plasma membrane of hit1-1 was less stable than that of the wild type, as determined by an electrolyte leakage assay, and enhanced leakage occurred before peroxidation injury to the membrane. In addition, the ability of hit1-1 to survive heat stress was not influenced by exposure to light, which suggested that the heat intolerance of hit-1 was a direct outcome of reduced membrane thermostability rather than heat-induced oxidative stress. Furthermore, hit1-1 was sensitive to the duration (sustained high temperature stress at 37 °C for 3 d) but not the intensity (heat shock at 44 °C for 30 min) of exposure to heat. Collectively, these results imply that HIT1 functions in the membrane trafficking that is involved in the thermal adaptation of the plasma membrane for tolerance to long-term heat stress in plants.
authors.affiliation: Department of Life Sciences, National Central University, No. 300, Jhong-da Road, Jhong-li City, Taoyuan 32001, Taiwan.
authors.forename: Lian-Chin
authors.initials: LC
authors.lastname: Wang
authors.forename: Ming-Chieh
authors.initials: MC
authors.lastname: Tsai
authors.forename: Kai-Yu
authors.initials: KY
authors.lastname: Chang
authors.forename: Yu-Shan
authors.initials: YS
authors.lastname: Fan
authors.forename: Ching-Hui
authors.initials: CH
authors.lastname: Yeh
authors.forename: Shaw-Jye
authors.initials: SJ
authors.lastname: Wu
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006358:Hot Temperature / Q000009:adverse effects*; D011485:Protein Binding; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C513833:Hit1 protein, Arabidopsis; D017392:Thiobarbituric Acid Reactive Substances; D002734:Chlorophyll