GSE132553
AtDXO1 possesses deNADding and exonuclease activities and plays pleiotropic roles in gene regulation
RNA capping and decapping tightly coordinate with transcription, translation, and RNA decay to regulate gene expression. The DXO/Rai1 family of proteins have been implicated in mRNA decapping and decay, and mammalian DXO was recently found to also function as a decapping enzyme for NAD+-capped RNAs (NAD-RNA). The Arabidopsis genome contains a single gene encoding a DXO/Rai1 protein, AtDXO1. Here we show that AtDXO1 possesses both NAD-RNA decapping activity and 5'-3' exonuclease activity and that the atdxo1 mutation increases the stability of NAD-RNAs. The atdxo1 mutant displays severe growth retardation, pale color, and multiple developmental defects. Transcriptome profiling analysis showed that the atdxo1 mutation leads to elevated expression of defense-related genes and down-regulation of photosynthesis genes. The autoimmunity phenotype of the mutant could be suppressed by either eds1 or npr1 mutation. Surprisingly, the various phenotypes associated with the atdxo1 mutant could be complemented by the enzymatically inactive AtDXO1. We found that AtDXO1 interacts with RNA cap methyltransferase (CMT). The atdxo1 mutation apparently enhances post-transcriptional gene silencing by elevating levels of siRNAs. Our study indicates that AtDXO1 regulates gene expression in various biological and physiological processes through its pleiotropic molecular functions in mediating RNA processing and decay. Overall design: Transcriptome and global small RNA analysis of atdxo1 mutants