The plastid protein THYLAKOID FORMATION1 and the plasma membrane G-protein GPA1 interact in a novel sugar-signaling mechanism in Arabidopsis
The plastid protein THYLAKOID FORMATION1 and the plasma membrane G-protein GPA1 interact in a novel sugar-signaling mechanism in Arabidopsis
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DOI：
10.1105/tpc.105.037259
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发表时间：
2006-05-01
期刊：
影响因子：
11.6
通讯作者：
Jones, AM
中科院分区：
文献类型：
--
作者：
Huang, J;Taylor, JP;Jones, AM
先前研究表明，编码异源三聚体 G 蛋白复合物成分的基因突变会改变对 D-葡萄糖水平增加的敏感性。这表明G蛋白偶联可能是拟南芥中一种新的糖信号传导机制。这里证明类囊体形成 1 (THF1) 在体内作为 G α 相互作用伴侣，在 D-葡萄糖信号通路中质膜分隔的异三聚体 G 蛋白 (GPA1) 下游发挥作用。 THF1 是一种定位于质体外膜和基质的质体蛋白。根质体 THF1 和 GPA1 在质膜上的接触发生在质体膜邻接质膜的位置，如福斯特共振能量转移 (FRET) 所证明的。生化和遗传证据都证明了 THF1 在糖信号传导中可能发挥的作用。 thf1-1无效突变体中的根生长对外源D-葡萄糖高度敏感，并且THF1过表达的根对高D-葡萄糖对生长速率的抑制具有抵抗力。此外，THF1 水平会被 D-葡萄糖迅速降解，但不会被 L-葡萄糖降解。 THF1 和 GPA1 之间的相互作用已通过体外和体内免疫共沉淀、FRET 分析和遗传上位性得到证实，并为质体和质膜之间的糖信号传导机制提供了证据。
Mutations in genes encoding components of the heterotrimeric G-protein complex were previously shown to confer altered sensitivity to increased levels of D-glucose. This suggests that G-protein coupling may be a novel sugar-signaling mechanism in Arabidopsis thaliana. THYLAKOID FORMATION1 (THF1) is here demonstrated in vivo as a G alpha interaction partner that functions downstream of the plasma membrane-delimited heterotrimeric G-protein (GPA1) in a D-glucose signaling pathway. THF1 is a plastid protein localized to both the outer plastid membrane and the stroma. Contact between root plastidic THF1 and GPA1 at the plasma membrane occurs at sites where the plastid membrane abuts the plasma membrane, as demonstrated by Forster resonance energy transfer ( FRET). A probable role for THF1 in sugar signaling is demonstrated by both biochemical and genetic evidence. Root growth in the thf1-1 null mutant is hypersensitive to exogenous D-glucose, and THF1-overexpressing roots are resistant to inhibition of growth rate by high D-glucose. Additionally, THF1 levels are rapidly degraded by D-glucose but not L-glucose. The interaction between THF1 and GPA1 has been confirmed by in vitro and in vivo coimmunoprecipitation, FRET analysis, and genetic epistasis and provides evidence of a sugar-signaling mechanism between plastids and the plasma membrane.