Peres Adrian, Churchman Michelle L, Hariharan Srivaidehirani, Himanen Kristiina, Verkest Aurine, Vandepoele Klaas, Magyar Zoltan, Hatzfeld Yves, Van Der Schueren Els, Beemster Gerrit T S, Frankard Valerie, Larkin John C, Inzé Dirk, De Veylder Lieven
CropDesign N.V., B-9052 Ghent, Belgium.
J Biol Chem. 2007 Aug 31;282(35):25588-96. doi: 10.1074/jbc.M703326200. Epub 2007 Jun 28.
The EL2 gene of rice (Oryza sativa), previously classified as early response gene against the potent biotic elicitor N-acetylchitoheptaose and encoding a short polypeptide with unknown function, was identified as a novel cell cycle regulatory gene related to the recently reported SIAMESE (SIM) gene of Arabidopsis thaliana. Iterative two-hybrid screens, in vitro pull-down assays, and fluorescence resonance energy transfer analyses showed that Orysa; EL2 binds the cyclin-dependent kinase (CDK) CDKA1;1 and D-type cyclins. No interaction was observed with the plant-specific B-type CDKs. The amino acid motif ELERFL was identified to be essential for cyclin, but not for CDK binding. Orysa;EL2 impaired the ability of Orysa; CYCD5;3 to complement a budding yeast (Saccharomyces cerevisiae) triple CLN mutant, whereas recombinant protein inhibited CDK activity in vitro. Moreover, Orysa;EL2 was able to rescue the multicellular trichome phenotype of sim mutants of Arabidopsis, unequivocally demonstrating that Orysa;EL2 operates as a cell cycle inhibitor. Orysa;EL2 mRNA levels were induced by cold, drought, and propionic acid. Our data suggest that Orysa;EL2 encodes a new type of plant CDK inhibitor that links cell cycle progression with biotic and abiotic stress responses.
水稻（Oryza sativa）的EL2基因，先前被归类为对强效生物激发子N-乙酰基七聚壳寡糖的早期反应基因，编码一种功能未知的短多肽，现被鉴定为与最近报道的拟南芥SIAMESE（SIM）基因相关的新型细胞周期调控基因。迭代双杂交筛选、体外下拉分析和荧光共振能量转移分析表明，水稻EL2与细胞周期蛋白依赖性激酶（CDK）CDKA1;1和D型细胞周期蛋白结合。未观察到与植物特异性B型CDK的相互作用。已确定氨基酸基序ELERFL对细胞周期蛋白结合至关重要，但对CDK结合并非如此。水稻EL2削弱了水稻CYCD5;3互补芽殖酵母（Saccharomyces cerevisiae）三重CLN突变体的能力，而重组蛋白在体外抑制了CDK活性。此外，水稻EL2能够挽救拟南芥sim突变体的多细胞毛状体表型，明确证明水稻EL2作为细胞周期抑制剂发挥作用。水稻EL2的mRNA水平受冷、干旱和丙酸诱导。我们的数据表明，水稻EL2编码一种新型植物CDK抑制剂，将细胞周期进程与生物和非生物胁迫反应联系起来。
