Genetic Analysis of DEFECTIVE KERNEL1 Loop Function in Three-Dimensional Body Patterning in Physcomitrella patens
Genetic Analysis of DEFECTIVE KERNEL1 Loop Function in Three-Dimensional Body Patterning in Physcomitrella patens
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DOI：
10.1104/pp.114.243758
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发表时间：
2014-10-01
期刊：
影响因子：
7.4
通讯作者：
Olsen, Odd-Arne
中科院分区：
文献类型：
--
作者：
Demko, Viktor;Perroud, Pierre-Francois;Olsen, Odd-Arne
高等植物缺陷KERNEL1 （DEK1）在位置依赖性信号传导中起重要作用，由一个与蛋白酶催化结构域和调控结构域相连的大跨膜结构域（MEM）组成。本研究表明，MEM结构域的感觉回路在苔藓小壶菌DEK1活性的发育调控中起着重要作用。与缺乏DEK1 （Delta DEK1）的patens相比，DEK1 Delta环突变体正确定位了芽顶细胞的分裂面。与Delta dek1芽的早期发育停滞相反，由于有丝分裂活性的错误调节，dek1 Delta环发育异常的配子体缺乏扩大的phylliks。与蛋白酶催化结构域高度保守的序列相反，陆生植物的环是高度可变的。从功能上来说，来自多态Marchantia的序列完全补充了dek1 Delta环表型，而来自玉米（Zea mays）和拟南芥（Arabidopsis thaliana）的序列则具有生长迟缓和影响叶根发育的表型。生物信息学分析确定MEM是主要促进者超家族的一员，这是一种对外部环境刺激作出反应的膜转运蛋白。通过比较野生型和Delta型dek1组织的转录组分析，确定了对与dek1突变表型相关的两组转录本的影响：与细胞壁重塑和调节AINTEGUMENTA、glut和BABY BOOM2 （APB2）和APB3转录因子相关的转录本，这些转录因子已知可调节芽的形成。最后，序列数据支持了进化成祖先陆地植物的高级绿藻失去细胞质钙蛋白酶的假设，保留了DEK1作为进化的陆地植物谱系中唯一的钙蛋白酶。
DEFECTIVE KERNEL1 (DEK1) of higher plants plays an essential role in position-dependent signaling and consists of a large transmembrane domain (MEM) linked to a protease catalytic domain and a regulatory domain. Here, we show that the postulated sensory Loop of the MEM domain plays an important role in the developmental regulation of DEK1 activity in the moss Physcomitrella patens. Compared with P. patens lacking DEK1 (Delta dek1), the dek1 Delta loop mutant correctly positions the division plane in the bud apical cell. In contrast with an early developmental arrest of Delta dek1 buds, dek1 Delta loop develops aberrant gametophores lacking expanded phyllids resulting from misregulation of mitotic activity. In contrast with the highly conserved sequence of the protease catalytic domain, the Loop is highly variable in land plants. Functionally, the sequence from Marchantia polymorpha fully complements the dek1 Delta loop phenotype, whereas sequences from maize (Zea mays) and Arabidopsis (Arabidopsis thaliana) give phenotypes with retarded growth and affected phyllid development. Bioinformatic analysis identifies MEM as a member of the Major Facilitator Superfamily, membrane transporters reacting to stimuli from the external environment. Transcriptome analysis comparing wild-type and Delta dek1 tissues identifies an effect on two groups of transcripts connected to dek1 mutant phenotypes: transcripts related to cell wall remodeling and regulation of the AINTEGUMENTA, PLETHORA, and BABY BOOM2 (APB2) and APB3 transcription factors known to regulate bud initiation. Finally, sequence data support the hypothesis that the advanced charophyte algae that evolved into ancestral land plants lost cytosolic calpains, retaining DEK1 as the sole calpain in the evolving land plant lineage.