a nucleotide metabolite controls stress-responsive gene expression and plant development核苷酸代谢控制逆境应答基因表达和植物的发展.pdfVIP

A Nucleotide Metabolite Controls Stress-Responsive Gene Expression and Plant Development 1,2 1 1 1,2 Hao Chen , Baichen Zhang , Leslie M. Hicks , Liming Xiong * 1 Donald Danforth Plant Science Center, St Louis, Missouri, United States of America, 2 Division of Chemical and Life Sciences Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia Abstract Abiotic stress, such as drought and high salinity, activates a network of signaling cascades that lead to the expression of many stress-responsive genes in plants. The Arabidopsis FIERY1 (FRY1) protein is a negative regulator of stress and abscisic acid (ABA) signaling and exhibits both an inositol polyphosphatase and a 39,59-bisphosphate nucleotidase activity in vitro. The FRY1 nucleotidase degrades the sulfation byproduct 3 9-phosphoadenosine-59-phosphate (PAP), yet its in vivo functions and particularly its roles in stress gene regulation remain unclear. Here we developed a LC-MS/MS method to quantitatively measure PAP levels in plants and investigated the roles of this nucleotidase activity in stress response and plant development. It was found that PAP level was tightly controlled in plants and did not accumulate to any significant level either under normal conditions or under NaCl, LiCl, cold, or ABA treatments. In contrast, high levels of PAP were detected in multiple mutant alleles of FRY1 but not in mutants of other FRY1 family members, indicating that FRY1 is the major enzyme that hydrolyzes PAP in vivo. By genetically reducing PAP levels in fry1 mutants either through overexpression of a yeast PAP nucleotidase or by generating a triple mutant of fry1 apk1 apk2 that is defective in the biosynthesis of the PAP precursor 3 9- phosphoad