Poly(A) tail (PAT) shortening, also termed deadenylation, is the rate-limiting step of mRNA degradation in eukaryotic cells. The carbon catabolite repressor 4-associated factor 1s (CAF1s) were shown to be one of the major enzymes for catalyzing mRNA deadenylation in yeast and mammalian cells. However, the functions of CAF1 proteins in plants are poorly understood. Herein, a sugar-upregulated CAF1 gene, OsCAF1B, is investigated in rice. Using gain–of–function and dominant-negative mutation analysis, we show that overexpression of OsCAF1B resulted in an accelerated α-amylase gene (αAmy3) mRNA degradation phenomenon, while ectopic expression of a form of OsCAF1B that had lost its deadenylase activity resulted in a delayed αAmy3 mRNA degradation phenomenon in transgenic rice cells. The change in αAmy3 mRNA degradation in transgenic rice is associated with the altered lengths of the αAmy3 mRNA PAT, indicating that OsCAF1B acts as a negative regulator of αAmy3 mRNA stability in rice. Additionally, we found that overexpression of OsCAF1B retards seed germination and seedling growth. These findings indicate that OsCAF1B participates in sugar-induced αAmy3 mRNA degradation and deadenylation and acts a negative factor for germination and seedling development.

中文翻译：

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CCR4关联因子1，OsCAF1B，参与αAmy3mRNA Poly（A）尾巴的缩短，并在发芽和幼苗生长中起作用

聚（A）尾（PAT）缩短，也称为腺苷酸化，是真核细胞中mRNA降解的限速步骤。碳分解代谢物阻遏物4相关因子1s（CAF1s）被证明是催化酵母和哺乳动物细胞中mRNA腺苷酸化的主要酶之一。但是，人们对CAF1蛋白在植物中的功能了解甚少。在本文中，在水稻中研究了糖上调的CAF1基因OsCAF1B。使用功能获得和显性负突变分析，我们显示OsCAF1B的过表达导致加速的α-淀粉酶基因（αAmy3）mRNA降解现象，而异位表达的形式的OsCAF1B失去了其腺苷酸酶活性导致转基因水稻细胞中αAmy3mRNA的延迟降解现象。转基因水稻中αAmy3mRNA降解的变化与αAmy3mRNA PAT长度的改变有关，这表明OsCAF1B充当水稻αAmy3mRNA稳定性的负调控因子。此外，我们发现OsCAF1B的过度表达会延迟种子发芽和幼苗生长。这些发现表明，OsCAF1B参与了糖诱导的αAmy3mRNA降解和去甲腺苷酸化作用，并对发芽和幼苗发育产生了负面影响。