State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Life Sciences Building, 5 Yi He Yuan Road, Haidian, Beijing 100871, China.
Mol Plant. 2013 Sep;6(5):1661-72. doi: 10.1093/mp/sst071. Epub 2013 May 8.
In plants, the cytokinin metabolic processes, including cytokinin biosynthesis, interconversion, inactivation, and degradation, play critical roles in the regulation of cytokinin homeostasis and plant development. Purine metabolic enzymes have been implied to catalyze the cytokinin interconversion in previous works. In this study, we report that Adenine Phosphoribosyl Transferase 1 (APT1) is the causal gene of the high-dose cytokinin-resistant mutants. APT1 catalyzes the cytokinin conversion from free bases to nucleotides, and is functionally predominant among the five members of the Arabidopsis Adenine Phosphoribosyl Transferase family. Loss of APT1 activity in plants leads to excess accumulation of cytokinin bases, thus evoking myriad cytokinin-regulated responses, such as delayed leaf senescence, anthocyanin accumulation, and downstream gene expression. Thus, our study defines APT1 as a key metabolic enzyme participating in the cytokinin inactivation by phosphoribosylation.
在植物中，细胞分裂素代谢过程，包括细胞分裂素的生物合成、相互转化、失活和降解，在细胞分裂素的动态平衡和植物发育的调控中起着关键作用。嘌呤代谢酶被认为在前人的工作中催化细胞分裂素的相互转化。在这项研究中，我们报告说腺嘌呤磷酸核糖基转移酶 1（APT1）是高剂量细胞分裂素抗性突变体的原因基因。APT1催化细胞分裂素从游离碱基转化为核苷酸，在拟南芥腺嘌呤磷酸核糖基转移酶家族的五个成员中具有功能优势。植物中 APT1 活性的丧失会导致细胞分裂素碱基的过度积累，从而引发许多细胞分裂素调节的反应，如延迟叶片衰老、花色素苷积累和下游基因表达。因此，我们的研究将 APT1 定义为参与通过磷酸核糖基化使细胞分裂素失活的关键代谢酶。
