Laxa Miriam, Müller Kristin, Lange Natalie, Doering Lennart, Pruscha Jan Thomas, Peterhänsel Christoph
Leibniz University Hannover, Institute of Botany, 30419 Hannover, Germany
Leibniz University Hannover, Institute of Botany, 30419 Hannover, Germany.
Plant Physiol. 2016 Sep;172(1):313-27. doi: 10.1104/pp.16.00881. Epub 2016 Jul 14.
Photorespiration is essential for the detoxification of glycolate and recycling of carbon to the Calvin Benson Bassham cycle. Enzymes participating in the pathway have been identified, and investigations now focus on the regulation of photorespiration by transporters and metabolites. However, regulation of photorespiration on the gene level has not been intensively studied. Here, we show that maximum transcript abundance of Glu:glyoxylate aminotransferase 1 (GGT1) is regulated by intron-mediated enhancement (IME) of the 5' leader intron rather than by regulatory elements in the 5' upstream region. The intron is rich in CT-stretches and contains the motif TGTGATTTG that is highly similar to the IME-related motif TTNGATYTG. The GGT1 intron also confers leaf-specific expression of foreign promoters. Quantitative PCR analysis and GUS activity measurements revealed that IME of the GGT1 5'UTR intron is controlled on the transcriptional level. IME by the GGT1 5'UTR intron was at least 2-fold. Chromatin immunoprecipitation experiments showed that the abundance of RNA polymerase II binding to the intron-less construct is reduced.
光呼吸对于乙醇酸的解毒以及碳向卡尔文-本森-巴斯姆循环的再循环至关重要。参与该途径的酶已被鉴定出来，目前的研究重点是转运蛋白和代谢物对光呼吸的调节。然而，光呼吸在基因水平上的调节尚未得到深入研究。在这里，我们表明谷氨酸：乙醛酸转氨酶1（GGT1）的最大转录本丰度是由5'前导内含子的内含子介导增强（IME）调节的，而不是由5'上游区域的调控元件调节。该内含子富含CT序列，并且包含与IME相关基序TTNGATYTG高度相似的基序TGTGATTTG。GGT1内含子还赋予外源启动子叶片特异性表达。定量PCR分析和GUS活性测量表明，GGT1 5'UTR内含子的IME在转录水平上受到控制。GGT1 5'UTR内含子的IME至少为2倍。染色质免疫沉淀实验表明，与无内含子构建体结合的RNA聚合酶II的丰度降低。
