title: EHB1 and AGD12, two calcium-dependent proteins affect gravitropism antagonistically in Arabidopsis thaliana.
abstract: The ADP-RIBOSYLATION FACTOR GTPase-ACTIVATING PROTEIN (AGD) 12, a member of the ARF-GAP protein family, affects gravitropism in Arabidopsis thaliana. A loss-of-function mutant lacking AGD12 displayed diminished gravitropism in roots and hypocotyls indicating that both organs are affected by this regulator. AGD12 is structurally related to ENHANCED BENDING (EHB) 1, previously described as a negative effector of gravitropism. In contrast to agd12 mutants, ehb1 loss-of function seedlings displayed enhanced gravitropic bending. While EHB1 and AGD12 both possess a C-terminal C2/CaLB-domain, EHB1 lacks the N-terminal ARF-GAP domain present in AGD12. Subcellular localization analysis using Brefeldin A indicated that both proteins are elements of the trans Golgi network. Physiological analyses provided evidence that gravitropic signaling might operate via an antagonistic interaction of ARF-GAP (AGD12) and EHB1 in their Ca2+-activated states.
authors.affiliation: Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany. Electronic address: duemmer@Staff.Uni-Marburg.DE.
authors.forename: Michaela
authors.initials: M
authors.lastname: Dümmer
authors.affiliation: Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany. Electronic address: michalsk@Staff.uni-marburg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Michalski
authors.affiliation: Fachbereich Chemie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany. Electronic address: essenl@staff.uni-marburg.de.
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Essen
authors.affiliation: Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany. Electronic address: magnus.rath@biologie.uni-marburg.de.
authors.forename: Magnus
authors.initials: M
authors.lastname: Rath
authors.affiliation: Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany. Electronic address: galland@biologie.uni-marburg.de.
authors.forename: Paul
authors.initials: P
authors.lastname: Galland
authors.affiliation: Institut für Biologie, Universität Siegen, Adolf-Reichwein Str. 2, D-57068 Siegen, Germany. Electronic address: forreiter@biologie.uni-siegen.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Forreiter
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D064527:Etiolation / Q000187:drug effects; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000378:metabolism*; D018522:Gravitropism / Q000187:drug effects*; D018519:Meristem / Q000187:drug effects / Q000502:physiology; D009154:Mutation / Q000235:genetics; D000072417:Protein Domains; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: C000616974:AGD12 protein, Arabidopsis; D029681:Arabidopsis Proteins; C000597452:EHB1 protein, Arabidopsis; D020690:GTPase-Activating Proteins; D002118:Calcium
keywords: Arabidopsis; Calcium dependent signalling; Gravitropism; Hypocotyl bending; Root bending; Signaling