1. ROSY1, a novel regulator of gravitropic response is a stigmasterol binding protein
- Author
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Gloria K. Muday, Erica M. Brown, Jyoti Dalal, Heike Sederoff, Christopher S. Brown, Daniel R. Lewis, Olaf Tietz, and Klaus Palme
- Subjects
0301 basic medicine ,Physiology ,Gravitropism ,Gravity ,Stigmasterol ,Arabidopsis ,Plant Science ,03 medical and health sciences ,Auxin ,Arabidopsis thaliana ,Amino Acid Sequence ,Phylogeny ,Sterol ,chemistry.chemical_classification ,biology ,Indoleacetic Acids ,Membrane transport protein ,Arabidopsis Proteins ,Binding protein ,Biological Transport ,Lipid ,biology.organism_classification ,030104 developmental biology ,Membrane protein ,Biochemistry ,chemistry ,Root ,Organ Specificity ,Membrane composition ,biology.protein ,Biophysics ,Carrier Proteins ,Sequence Alignment ,Agronomy and Crop Science ,Basipetal auxin transport - Abstract
The gravitropic bending in plant roots is caused by asymmetric cell elongation. This requires an asymmetric increase in cell surface and therefore plasma membrane components such as lipids, sterols, and membrane proteins. We have identified an early gravity-regulated protein in Arabidopsis thaliana root apices that binds stigmasterol and phosphoethanolamines. This root-specific protein interacts with the membrane transport protein synaptotagmin-1 and was therefore named InteractoR Of SYnaptotagmin1 (ROSY1). While interactions between ML-domain proteins with membrane transport proteins and their impact have been reported from animal cell systems, this is the first report of such an interaction in a plant system. Homozygous mutants of ROSY1 exhibit decreased basipetal auxin transport, a faster root gravitropic response, and an increase in salt stress tolerance. Our results suggest that ROSY1 plays a role in root gravitropism, possibly by facilitating membrane trafficking and asymmetric cell elongation via its interaction with synaptotagmin-1.
- Published
- 2016
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