A Framework for Lateral Membrane Trafficking and Polar Tethering of the PEN3 ATP-Binding Cassette Transporter.
The outermost cell layer of plants, the epidermis, and its outer (lateral) membrane domain facing the environment are continuously challenged by biotic and abiotic stresses. Therefore, the epidermis and the outer membrane domain provide important selective and protective barriers. However, only a small number of specifically outer membrane-localized proteins are known. Similarly, molecular mechanisms underlying the trafficking and the polar placement of outer membrane domain proteins require further exploration. Here, we demonstrate that ACTIN7 (ACT7) mediates trafficking of the PENETRATION3 (PEN3) outer membrane protein from the trans-Golgi network (TGN) to the plasma membrane in the root epidermis of Arabidopsis (Arabidopsis thaliana) and that actin function contributes to PEN3 endocytic recycling. In contrast to such generic ACT7-dependent trafficking from the TGN, the EXOCYST84b (EXO84b) tethering factor mediates PEN3 outer-membrane polarity. Moreover, precise EXO84b placement at the outer membrane domain itself requires ACT7 function. Hence, our results uncover spatially and mechanistically distinct requirements for ACT7 function during outer lateral membrane cargo trafficking and polarity establishment. They further identify an exocyst tethering complex mediator of outer lateral membrane cargo polarity.
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and.|Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.).
Hailiang
H
Mao
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and.|Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.).
Moritaka
M
Nakamura
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and.|Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.).
Corrado
C
Viotti
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, SE-90 187 Umeå, Sweden (H.M., M.G.); and markus.grebe@uni-potsdam.de.|Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam-Golm, Germany (M.N., C.V., M.G.) markus.grebe@uni-potsdam.de.
Markus
0000-0001-7571-0670
M
Grebe
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D003593:Cytoplasm / Q000378:metabolism; D004705:Endocytosis; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D055571:Secretory Pathway; D021601:trans-Golgi Network / Q000378:metabolism / Q000648:ultrastructure
D018528:ATP-Binding Cassette Transporters; D000199:Actins; D029681:Arabidopsis Proteins; D015415:Biomarkers; C510424:PDR8 protein, Arabidopsis