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植物叶绿素生物合成途径(镁分支)中的第一个酶是镁离子螯合酶,它由I(ChlI)、D(ChlD)和H(ChlH)三个亚基组成.各亚基不仅参与叶绿素的生物合成,而且还与叶绿体到细胞核的反向信号传导有关.Gun4是一个卟啉结合蛋白,它能提高植物镁离子螯合酶的活性,在缺乏Gun4的条件下,镁离子螯合酶整个复合物非常不稳定,不足以开始催化反应.我们以前的研究发现,Gun4的C末端几个氨基酸具有重要作用.在本文中,通过缺失突变,获得了C端缺失了8个氨基酸残基突变的Gun4(Gun4L).酵母双杂交与GST-pull down实验发现,Gun4L仍能与H亚基相互作用,原核表达和纯化Gun4L和镁离子螯合酶各亚基后,重组镁离子螯合酶的酶活分析证实,Gun4L对镁离子螯合酶的活性失去了激活作用.
The first enzyme in the plant chlorophyll biosynthesis pathway (magnesium branch) is a magnesium ion chelating enzyme consisting of three subunits: ChlI, D (ChlD) and H (ChlH) And is also involved in the reverse signal transduction of the chloroplast to the nucleus.Gun4 is a porphyrin-binding protein that enhances the activity of magnesium ion chelatase in the absence of Gun4, The complex is not very stable enough to start the catalytic reaction.Our previous study found that several amino acids at the C-terminal of Gun4 play an important role.In this paper, we deleted the C-terminal deletion of 8 amino acid residues Gun4 (Gun4L) yeast two-hybrid and GST-pull down experiments found that Gun4L can still interact with the H subunit, prokaryotic expression and purification of Gun4L and magnesium ion chelating enzyme subunits, the recombinant magnesium ion chelating enzyme Live analysis confirmed that Gun4L lost the activation of magnesium chelatase activity.