Translation Co-factor PABP-interacting protein 11 moonlights as a transcriptional activator to modulate callose synthesis gene expression.

Abstract

The development of rice fertility is a complex process, which is precisely regulated by numerous genes. In this study, we cloned and characterized OsPAIP11, a PABP-interacting protein that functions as an auxiliary factor in translation initiation. The ospaip11 exhibited multiple defects, including impaired callose synthesis, delayed tapetum apoptosis, and abnormal pollen wall development, which are essentially consistent with the phenotype of the allelic mutant dcet1. Subcellular localization analysis revealed that OsPAIP11 is localized in both the cytoplasm and nucleus. Interestingly, further investigation demonstrated that the RRM2 domain of OsPAIP11 exhibits transcriptional activation activity. Moreover, OsPAIP11 directly binds to the promoter of the callose synthesis-related genes GLUCAN SYNTHASE-LIKE 5 (OsGSL5) and OsGAMYB, thereby regulating their transcription and influencing callose biosynthesis during pollen development. Additionally, OsPAIP11 also interacts with the translation initiation factor and auxiliary factors. These findings suggest that OsPAIP11 modulates male fertility primarily by regulating the transcription of callose synthesis-related genes and may also participate in the translation process.