Phosphatidylinositol 4-Phosphate Negatively Regulates Chloroplast Division in Arabidopsis
Phosphatidylinositol 4-Phosphate Negatively Regulates Chloroplast Division in Arabidopsis
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DOI：
10.1105/tpc.115.136234
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发表时间：
2015-03-01
期刊：
影响因子：
11.6
通讯作者：
Wada, Hajime
中科院分区：
文献类型：
--
作者：
Okazaki, Kumiko;Miyagishima, Shin-ya;Wada, Hajime
叶绿体的分裂是由被膜在分裂部位的收缩完成的。虽然环状蛋白质复合物的收缩已被证明参与叶绿体分裂，但膜脂如何参与这一过程仍不清楚。在这里，我们表明，在包膜膜未知功能的磷酸肌醇参与调节拟南芥叶绿体分裂。PLASTID DIVISION 1（PDV 1）和PDV 2蛋白与磷脂酰肌醇4-磷酸（PI 4P）特异性相互作用。抑制磷脂酰肌醇4-激酶（PI 4K）可降低叶绿体中PI 4P的水平，促进叶绿体分裂。敲除PI 4 K β 2表达或下调PI 4 K α 1表达导致叶绿体中PI 4 P水平降低并增加叶绿体数量。PI 4K α 1是叶绿体中PI 4P合成的主要贡献者，并且在pdv 1突变体中PI 4K抑制的效果在很大程度上被消除。过表达的蛋白质相关蛋白5 B（DRP 5 B），另一个组成部分的叶绿体分裂机制，这是招募到叶绿体的PDV 1和PDV 2，增强了PI 4K抑制的效果，而过表达的PDV 1和PDV 2有累加效应。与叶绿体结合的DRP 5 B的量在PI 4K抑制后增加。这些发现表明，PI 4P是一个调节器的叶绿体分裂的PDV 1和DRP 5 B依赖的方式。
Chloroplast division is performed by the constriction of envelope membranes at the division site. Although constriction of a ring-like protein complex has been shown to be involved in chloroplast division, it remains unknown how membrane lipids participate in the process. Here, we show that phosphoinositides with unknown function in envelope membranes are involved in the regulation of chloroplast division in Arabidopsis thaliana. PLASTID DIVISION1 (PDV1) and PDV2 proteins interacted specifically with phosphatidylinositol 4-phosphate (PI4P). Inhibition of phosphatidylinositol 4-kinase (PI4K) decreased the level of PI4P in chloroplasts and accelerated chloroplast division. Knockout of PI4K beta 2 expression or downregulation of PI4K alpha 1 expression resulted in decreased levels of PI4P in chloroplasts and increased chloroplast numbers. PI4K alpha 1 is the main contributor to PI4P synthesis in chloroplasts, and the effect of PI4K inhibition was largely abolished in the pdv1 mutant. Overexpression of DYNAMIN-RELATED PROTEIN5B (DRP5B), another component of the chloroplast division machinery, which is recruited to chloroplasts by PDV1 and PDV2, enhanced the effect of PI4K inhibition, whereas overexpression of PDV1 and PDV2 had additive effects. The amount of DRP5B that associated with chloroplasts increased upon PI4K inhibition. These findings suggest that PI4P is a regulator of chloroplast division in a PDV1- and DRP5B-dependent manner.