Shenzhen Key Laboratory of Synthetic Genomics, Guangdong Provincial Key Laboratory of Synthetic Genomics, Key Laboratory of Quantitative Synthetic Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Sci Adv. 2024 Jan 12;10(2):eadk0738. doi: 10.1126/sciadv.adk0738. Epub 2024 Jan 10.
The aromatic amino acids (AAAs) phenylalanine, tyrosine, and tryptophan are basic protein units and precursors of diverse specialized metabolites that are essential for plant growth. Despite their significance, the mechanisms that regulate AAA homeostasis remain elusive. Here, we identified a cytosolic aromatic aminotransferase, REVERSAL OF SAV3 PHENOTYPE 1 (VAS1), as a suppressor of () in Arabidopsis (). Genetic and biochemical analyses determined that VAS1 uses AAAs as amino donors, leading to the formation of 3-carboxyphenylalanine and 3-carboxytyrosine. These pathways represent distinct routes for AAA metabolism that are unique to specific plant species. Furthermore, we show that VAS1 is responsible for cytosolic AAA biosynthesis, and its enzymatic activity can be inhibited by 3-carboxyphenylalanine. These findings provide valuable insights into the crucial role of VAS1 in producing 3-carboxy AAAs, notably via recycling of AAAs in the cytosol, which maintains AAA homeostasis and allows plants to effectively coordinate the complex metabolic and biosynthetic pathways of AAAs.
芳香族氨基酸（AAAs）苯丙氨酸、酪氨酸和色氨酸是基本的蛋白质单位，也是各种特殊代谢物的前体，对植物生长至关重要。尽管它们很重要，但调节 AAA 动态平衡的机制仍难以捉摸。在这里，我们鉴定了一种细胞质芳香族氨基转移酶，即 REVERSAL OF SAV3 PHENOTYPE 1（VAS1），它可以作为拟南芥（）中 () 的抑制因子。遗传和生化分析确定，VAS1 将 AAAs 用作氨基供体，导致 3-羧基苯丙氨酸和 3-羧基酪氨酸的形成。这些途径代表了 AAA 代谢的独特途径，是特定植物物种所特有的。此外，我们表明 VAS1 负责细胞质 AAA 的生物合成，其酶活性可被 3-羧基苯丙氨酸抑制。这些发现为 VAS1 在产生 3-羧基 AAAs 中的关键作用提供了有价值的见解，特别是通过细胞质中 AAAs 的再循环，从而维持 AAA 动态平衡，并使植物能够有效地协调 AAAs 的复杂代谢和生物合成途径。
