title: Spatial Regulation of ABCG25, an ABA Exporter, Is an Important Component of the Mechanism Controlling Cellular ABA Levels.
abstract: The phytohormone abscisic acid (ABA) plays crucial roles in various physiological processes, including responses to abiotic stresses, in plants. Recently, multiple ABA transporters were identified. The loss-of-function and gain-of-function mutants of these transporters show altered ABA sensitivity and stomata regulation, highlighting the importance of ABA transporters in ABA-mediated processes. However, how the activity of these transporters is regulated remains elusive. Here, we show that spatial regulation of ATP BINDING CASETTE G25 (ABCG25), an ABA exporter, is an important mechanism controlling its activity. ABCG25, as a soluble green fluorescent protein (sGFP) fusion, was subject to posttranslational regulation via clathrin-dependent and adaptor protein complex-2-dependent endocytosis followed by trafficking to the vacuole. The levels of sGFP:ABCG25 at the plasma membrane (PM) were regulated by abiotic stresses and exogenously applied ABA; PM-localized sGFP:ABCG25 decreased under abiotic stress conditions via activation of endocytosis in an ABA-independent manner, but increased upon application of exogenous ABA via activation of recycling from early endosomes in an ABA-dependent manner. Based on these findings, we propose that the spatial regulation of ABCG25 is an important component of the mechanism by which plants fine-tune cellular ABA levels according to cellular and environmental conditions.
authors.affiliation: Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Youngmin
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Zheng-Yi
authors.initials: ZY
authors.lastname: Xu
authors.affiliation: Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Soo Youn
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Jihyeong
authors.initials: J
authors.lastname: Lee
authors.affiliation: Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Bongsoo
authors.identifier: 0000-0001-8869-4200
authors.initials: B
authors.lastname: Choi
authors.affiliation: Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Juhun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Center for Genome Engineering Institute for Basic Science, Yuseong-gu 305-811, Daejeon, South Korea.
authors.forename: Hyeran
authors.initials: H
authors.lastname: Kim
authors.affiliation: Center for Genome Engineering Institute for Basic Science, Yuseong-gu 305-811, Daejeon, South Korea.
authors.forename: Hee-Jung
authors.initials: HJ
authors.lastname: Sim
authors.affiliation: Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 790-784, Korea ihhwang@postech.ac.kr.|Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Inhwan
authors.identifier: 0000-0002-1388-1367
authors.initials: I
authors.lastname: Hwang
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000040:Abscisic Acid / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C000606829:ABCG25 protein, Arabidopsis; D018528:ATP-Binding Cassette Transporters; D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid