拟南芥PGK基因家族功能的初步分析

Functional analysis of PGK gene family in Arabidopsis

磷酸甘油酸激酶(Phosphoglycerate kinase)是一类进化上非常保守的蛋白家族,因而利用模式植物拟南芥研究PGK家族基因功能具有普遍意义。拟南芥基因组中含有三个PGK基因家族成员(PGK1,PGK2和PGK3),但是对于它们的基因表达模式和蛋白定位的研究还不是很清楚。本文利用实时荧光定量PCR技术检测了PGK基因家族的表达模式,结果表明三个PGK基因在拟南芥的各个组织器官和发育阶段中都有表达。利用拟南芥原生质体瞬时转化系统对三个PGK蛋白进行亚细胞定位,结果显示PGK1和PGK3定位于细胞基质,而PGK2定位于叶绿体。另外,我们分离得到了PGK2基因的T-DNA插入敲除突变体pgk2。pgk2在正常条件下表现出叶片黄化,PR1基因上调表达和H_2O_2过量积累等类似于超敏反应的细胞死亡表型。进一步的遗传分析表明pgk2的细胞死亡表型和T-DNA插入位点紧密连锁,暗示着pgk2的细胞死亡表型是由于PGK2的基因缺失造成的,因此PGK2可能在调控植物细胞程序化死亡过程中有重要作用。以上研究结果对于进一步探讨PGK基因家族的功能具有重要的参考价值。

Phosphoglycerate kinase （PGK） belongs to an evolutionarily conserved protein family. Therefore, investigation of the functions of PGK gene family using model plant Arabidopsis thaliana has universal significance. The genome of Arabidopsis thaliana contains three members of PGK gene （ PGK1, PGK2 and PGK3 ）, but the biological roles of these members are still unclear. In the present study, we examined the expression profiles of PGK gene family using real - time fluorescence quantitative PCR. Our findings suggested that all three members of PGK gene are able to express in different tissues in different development stages and its expression was tissue - specific and developmentally controlled. Meanwhile, the subcellular localizations of PGK proteins were analysed using the transient transformation of Arabidopsis protoplast. The results demon- strated that the PGK1 and PGK3 proteins were localized in the cytoplasm, while PGK2 localized in the chloroplast. Additionally we also isolated a putative PGK2 gene knockout mutant： pgk2. Interestingly, pgk2 exhibited hypersensitive response- like （HR） phenotypes under normal conditions. Further genetic analysis reveals that the HR - like phenotype is tightly linked to the T - DNA insertion at a single locus, which suggests PGK2＇ s involvement in the regulation of plant programmed cell death. These data will be helpful in gaining a deeper understanding of the functions of PGK gene family in plant.