title: Ubiquitination-Related MdBT Scaffold Proteins Target a bHLH Transcription Factor for Iron Homeostasis.
abstract: Iron (Fe) homeostasis is crucial for plant growth and development. A network of basic helix-loop-helix (bHLH) transcription factors positively regulates Fe uptake during iron deficiency. However, their up-regulation or overexpression leads to Fe overload and reactive oxygen species generation, thereby damaging the plants. Here, we found that two BTB/TAZ proteins, MdBT1 and MdBT2, interact with the MbHLH104 protein in apple. In addition, the function of MdBT2 was characterized as a regulator of MdbHLH104 degradation via ubiquitination and the 26S proteasome pathway, thereby controlling the activity of plasma membrane H+-ATPases and the acquisition of iron. Furthermore, MdBT2 interacted with MdCUL3 proteins, which were required for the MdBT2-mediated ubiquitination modification of MdbHLH104 and its degradation. In sum, our findings demonstrate that MdBT proteins interact with MdCUL3 to bridge the formation of the MdBTsMdCUL3complex, which negatively modulates the degradation of the MdbHLH104 protein in response to changes in Fe status to maintain iron homeostasis in plants.
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Yi-Ran
authors.identifier: 0000-0002-3748-3013
authors.initials: YR
authors.lastname: Ren
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Qing-Jie
authors.initials: QJ
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China.
authors.forename: Chun-Xiang
authors.initials: CX
authors.lastname: You
authors.affiliation: National Key Laboratory of Crop Biology, National Research Center for Apple Engineering and Technology, and College of Horticulture Science and Engineering, Shandong Agricultural University, Tai-An, Shandong 271018, China haoyujin@sdau.edu.cn.
authors.forename: Yu-Jin
authors.identifier: 0000-0003-2942-5910
authors.initials: YJ
authors.lastname: Hao
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D006706:Homeostasis / Q000187:drug effects*; D007501:Iron / Q000378:metabolism / Q000494:pharmacology*; D027845:Malus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D006180:Proton-Translocating ATPases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D058441:Rhizosphere; D054875:Ubiquitination / Q000187:drug effects*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D007501:Iron; D010940:Plant Proteins; D006180:Proton-Translocating ATPases; D017382:Reactive Oxygen Species