title: ROSY1, a novel regulator of gravitropic response is a stigmasterol binding protein.
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.
authors.affiliation: Dept. of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7621, United States.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Dalal
authors.affiliation: Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109, United States.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Lewis
authors.affiliation: University of Freiburg, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Tietz
authors.affiliation: Dept. of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7621, United States.
authors.forename: Erica M
authors.initials: EM
authors.lastname: Brown
authors.affiliation: Dept. of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7621, United States.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Brown
authors.affiliation: University of Freiburg, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Palme
authors.affiliation: Dept. of Biology, Wake Forest University, Winston-Salem, NC 27109, United States.
authors.forename: Gloria K
authors.initials: GK
authors.lastname: Muday
authors.affiliation: Dept. of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695-7621, United States. Electronic address: hwsedero@ncsu.edu.
authors.forename: Heike W
authors.initials: HW
authors.lastname: Sederoff
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D018522:Gravitropism; D007210:Indoleacetic Acids / Q000378:metabolism*; D009928:Organ Specificity; D010802:Phylogeny; D016415:Sequence Alignment; D013265:Stigmasterol / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D007210:Indoleacetic Acids; C000614894:ROSY1 protein, Arabidopsis; D013265:Stigmasterol
keywords: Arabidopsis; Auxin; Gravity; Lipid; Membrane composition; Root; Sterol