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Two forms of NAD-malic enzyme in maize leaves are regulated by light in opposite ways via promoter methylation
Journal of Plant Physiology ( IF 4.3 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.jplph.2020.153193
Alexander T Eprintsev 1 , Dmitry N Fedorin 1 , Marina O Gataullina 1 , Abir U Igamberdiev 2
Affiliation  

NAD-malic enzyme (EC 1.1.1.39) activity, expression and methylation of promoters of its two genes was studied in maize (Zea mays L.) leaves depending on light regime. The total activity was high in darkness and upon irradiation by far-red light and suppressed by white light and by red light. The changes in the levels of transcripts of the genes Me1 and Me2 encoding NAD-malic enzyme revealed their dependence on irradiation in opposite ways. White and red light decreased the quantity of mRNA of the gene Me1, while far-red light led to the increase of its transcripts. The opposite pattern was observed for the transcripts of Me2, the level of which was low in darkness and upon irradiation by far-red light, and was higher in white light and after irradiation by red light. The study of methylation of the promoters of the genes encoding NAD-ME showed a strong dependence between the levels of transcripts and the state of methylation of CG dinucleotides. The two isoforms of NAD-malic enzyme were partially purified from maize leaves and characterized. The first isoform had a pH optimum of 6.4 while the second had a pH optimum of 6.9; in the reverse reaction, the pH optimum was ∼0.5 units higher. It is concluded that the two genes encode different isoforms of NAD-malic enzyme with different kinetic properties. The role of both isoforms in the operation of the tricarboxylic acid cycle in the open mode is discussed.

中文翻译:

玉米叶片中两种形式的 NAD-苹果酸酶通过启动子甲基化以相反的方式受光调节

根据光照条件在玉米 (Zea mays L.) 叶子中研究了 NAD-苹果酸酶 (EC 1.1.1.39) 活性、其两个基因的启动子的表达和甲基化。总活性在黑暗和远红光照射下高,被白光和红光抑制。编码 NAD-苹果酸酶的基因 Me1 和 Me2 的转录水平的变化揭示了它们以相反的方式依赖辐射。白光和红光减少了基因Me1的mRNA数量,而远红光导致其转录物的增加。对于Me2的转录本观察到相反的模式,其在黑暗中和远红光照射后的水平较低,而在白光和红光照射后的水平较高。对编码 NAD-ME 的基因启动子甲基化的研究表明,转录水平与 CG 二核苷酸甲基化状态之间存在很强的依赖性。NAD-苹果酸酶的两种同工型从玉米叶中部分纯化并进行表征。第一个异构体的最适 pH 值为 6.4,而第二个异构体的最适 pH 值为 6.9;在逆反应中,最适 pH 值高出约 0.5 个单位。得出的结论是,这两个基因编码具有不同动力学特性的 NAD-苹果酸酶的不同同种型。讨论了两种异构体在开放模式下三羧酸循环操作中的作用。第一个异构体的最适 pH 值为 6.4,而第二个异构体的最适 pH 值为 6.9;在逆反应中,最适 pH 值高出约 0.5 个单位。得出的结论是,这两个基因编码具有不同动力学特性的 NAD-苹果酸酶的不同同种型。讨论了两种异构体在开放模式下三羧酸循环操作中的作用。第一个异构体的最适 pH 值为 6.4,而第二个异构体的最适 pH 值为 6.9;在逆反应中,最适 pH 值高出约 0.5 个单位。得出的结论是,这两个基因编码具有不同动力学特性的 NAD-苹果酸酶的不同同种型。讨论了两种异构体在开放模式下三羧酸循环操作中的作用。
更新日期:2020-08-01
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