Dümmer Michaela, Michalski Christian, Essen Lars-Oliver, Rath Magnus, Galland Paul, Forreiter Christoph
Fachbereich Biologie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany.
Fachbereich Chemie, Philipps-Universität Marburg, Karl-von-Frisch Str. 8, D-35032 Marburg, Germany.
J Plant Physiol. 2016 Nov 1;206:114-124. doi: 10.1016/j.jplph.2016.09.006. Epub 2016 Sep 30.
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 Ca-activated states.
ADP核糖基化因子GTP酶激活蛋白（AGD）12是ARF-GAP蛋白家族的成员之一，它影响拟南芥的向重力性。缺乏AGD12的功能缺失突变体在根和下胚轴中表现出减弱的向重力性，这表明这两个器官都受该调节因子的影响。AGD12在结构上与增强弯曲（EHB）1相关，EHB1先前被描述为向重力性的负效应因子。与agd12突变体相反，ehb1功能缺失的幼苗表现出增强的向重力性弯曲。虽然EHB1和AGD12都具有C端C2/CaLB结构域，但EHB1缺乏AGD12中存在的N端ARF-GAP结构域。使用布雷菲德菌素A进行的亚细胞定位分析表明，这两种蛋白质都是反式高尔基体网络的组成部分。生理学分析提供了证据，表明向重力性信号传导可能通过ARF-GAP（AGD12）和EHB1在其钙激活状态下的拮抗相互作用发挥作用。
