Complex Regulation of Prolyl-4-Hydroxylases Impacts Root Hair Expansion  

作　　者：Silvia M. Velasauez Martiniano M. Ricardi Christian Peter Poulsen Ai Oikawa Adiphol Dilokpimol Adnan Halim Silvina Mangano Silvina Paola Denita Juarez Eliana Marzol Juan D. Salgado Salter Javier Gloazzo Dorosz Cecilia Borassi Svenning Rune Moller Rafael Buono Yukiko Ohsawa Ken Matsuoka Marisa S. Otegui Henrik V. Scheller Naomi Geshi Bent Larsen Petersen Norberto D. lusem Jose M. Estevez 

机构地区：[1]Instituto de Fisiologfa, Biologia Molecular y Neurociencias (IFIBYNE-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires,Buenos Aires C1428EGA, Argentina [2]VKR Research Centre, Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frededksberg C, Denmark [3]Joint BioEnergy Institute, Feedstocks Division, Lawrence Berkeley National Laboratory, 5885 Hollis Street, Emeryville, CA 94608, USA [4]Copenhagen Center for Glycomios, Department of Cellular and Molecular, Faculty of Health and Medical Sciences, University of Copenhagen,DK-2200 Copenhagen N, Denmark [5]Department of Botany, University of Wisconsin, Madison, WI 53706, USA [6]RIKEN Plant Science Center, Tsurumi-ku, Yokohama 230-0045, Japan [7]Laboratory of Plant Nutrition, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan [8]Departamento de Fisiologia, Biologia Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EGA,Argentina [9]These authors contributed equally to the article. [10]Present address: Fungal Physiology, CBS-KNAW Fungal Biodiversity Center, Uppsalalaan 8, Utrecht 3584 CT, The Netherlands [11]Present address: The Danish Stem Cell Center, The Panum Institute, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark

出　　处：《Molecular Plant》2015年第5期734-746,共13页分子植物（英文版）

摘　　要：Root hairs are single cells that develop by tip growth, a process shared with pollen tubes, axons, and fungal hyphae. However, structural plant cell walls impose constraints to accomplish tip growth. In addition to polysaccharides, plant cell walls are composed of hydroxyproline-rich glycoproteins （HRGPs）, which include several groups of O-glycoproteins, including extensins （EXTs）. Proline hydroxylation, an early post-translational modification （PTM） of HRGPs catalyzed by prolyl 4-hydroxylases （P4Hs）, defines their subsequent O-glycosylation sites. In this work, our genetic analyses prove that P4H5, and to a lesser extent P4H2 and P4H13, are pivotal for root hair tip growth. Second, we demonstrate that P4H5 has in vitro preferred specificity for EXT substrates rather than for other HRGPs. Third, by P4H promoter and protein swapping approaches, we show that P4H2 and P4H13 have interchangeable functions but cannot replace P4H5. These three P4Hs are shown to be targeted to the secretory pathway, where P4H5 forms dimers with P4H2 and P4H13. Finally, we explore the impact of deficient proline hydroxylation on the cell wall architec- ture. Taken together, our results support a model in which correct peptidyl-proline hydroxylation on EXTs, and possibly in other HRGPs, is required for proper cell wall self-assembly and hence root hair elongation in Arabidopsis thaliana.Root hairs are single cells that develop by tip growth, a process shared with pollen tubes, axons, and fungal hyphae. However, structural plant cell walls impose constraints to accomplish tip growth. In addition to polysaccharides, plant cell walls are composed of hydroxyproline-rich glycoproteins （HRGPs）, which include several groups of O-glycoproteins, including extensins （EXTs）. Proline hydroxylation, an early post-translational modification （PTM） of HRGPs catalyzed by prolyl 4-hydroxylases （P4Hs）, defines their subsequent O-glycosylation sites. In this work, our genetic analyses prove that P4H5, and to a lesser extent P4H2 and P4H13, are pivotal for root hair tip growth. Second, we demonstrate that P4H5 has in vitro preferred specificity for EXT substrates rather than for other HRGPs. Third, by P4H promoter and protein swapping approaches, we show that P4H2 and P4H13 have interchangeable functions but cannot replace P4H5. These three P4Hs are shown to be targeted to the secretory pathway, where P4H5 forms dimers with P4H2 and P4H13. Finally, we explore the impact of deficient proline hydroxylation on the cell wall architec- ture. Taken together, our results support a model in which correct peptidyl-proline hydroxylation on EXTs, and possibly in other HRGPs, is required for proper cell wall self-assembly and hence root hair elongation in Arabidopsis thaliana.

关 键 词：ENZYMOLOGY cell expansion cell walls protein targeting proline hydroxylation root hairs 

分 类 号：Q946.889[生物学—植物学] TQ465.1[化学工程—制药化工]