Isolation and characterization of MdATG18a, a WD40-repeat AuTophaGy-related gene responsive to leaf senescence and abiotic stress in Malus

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• 作者：Ping Wang ; Xun Sun ; Zhiyong Yue ; Dong Liang ; Na Wang ; Fengwang Ma
• 关键词：ATG18 ; AuTophaGy-related gene 18 ; CRL4 ; cullin4-RING ubiquitin ligase complex ; Cvt ; cytoplasm-to-vacuole targeting ; DWD ; DNA-binding WD40 proteins ; EF-1伪 ; elongation factor 1 alpha gene ; ER ; endoplasmic reticulum ; MV ; methyl viologen ; ORF ; open reading frame ; PI3K ; phosphatidylinositol 3-kinase ; PI3P ; phosphatidylinositol 3-phosphate ; ROS ; reactive oxygen species ; TSPO ; tryptophan-rich sensory protein ; UPR ; unfolded protein response ; WIPI1 and WIPI2 ; WD-repeat protein-interacting phosphoinositi
• 刊名：Scientia Horticulturae
• 出版年：22 January, 2014
• 年：2014
• 卷：165
• 期：Complete
• 页码：51-61
• 全文大小：4808 K

文摘

Autophagy is an important means for recycling damaged cell components or degrading various proteins when plants are under starvation or oxidative stress. AuTophaGy-related gene 18 (ATG18), a phosphoinositide-binding protein that functions through the WD40 domain, is required for vesicle formation in autophagy. Here, we isolated and characterized MdATG18a from Malus domestica. Its full-length cDNA is a complete 1281 bp open reading frame (ORF) of nucleotides encoding a polypeptide of 426 amino acids. The deduced protein contains two WD40 domains. Phylogenetic analysis confirmed that MdATG18a clusters with Arabidopsis members AtATG18a, c, d, and e. The 3D structure has a seven-bladed 尾-propeller and two putative phosphatidylinositol 3-phosphate (PI3P) binding sites. When transiently expressed in onion epidermal cells, the MdATG18a-GFP fusion protein was localized in the nucleus and cell membrane. Prediction of a 1824 bp promoter region cloned from apple genome DNA indicated several key cis-regulatory elements involved in plant responses to abiotic stresses. MdATG18a was expressed in all tested tissues and showed obvious up-regulation under leaf senescence, drought, heat, oxidative stress, nitrogen starvation or ER stress. Taken together, our findings suggest that MdATG18a plays a role in responses to leaf senescence and abiotic stresses, which might be indicative of autophagy involved in mechanism regulation for stress tolerance in apple.