Affiliation:
1. National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology & Ecology Chinese Academy of Sciences Shanghai 200032 China
2. University of the Chinese Academy of Sciences Beijing 100049 China
3. Institute of Molecular Breeding for Maize Qilu Normal University Jinan 250200 China
4. College of Life Science Shanghai Normal University 100 Guilin Road Shanghai 200233 China
Abstract
Summary
Nuclear‐cytoplasmic trafficking is crucial for protein synthesis in eukaryotic cells due to the spatial separation of transcription and translation by the nuclear envelope. However, the mechanism underlying this process remains largely unknown in plants.
In this study, we isolated a maize (Zea mays) mutant designated developmentally delayed kernel 1 (ddk1), which exhibits delayed seed development and slower filling. Ddk1 encodes a plant‐specific protein known as Importin‐4 β, and its mutation results in reduced 80S monosomes and suppressed protein synthesis.
Through our investigations, we found that DDK1 interacts with eIF1A proteins in vivo. However, in vitro experiments revealed that this interaction exhibits low affinity in the absence of RanGTP. Additionally, while the eIF1A protein primarily localizes to the cytoplasm in the wild‐type, it remains significantly retained within the nuclei of ddk1 mutants. These observations suggest that DDK1 functions as an exportin and collaborates with RanGTP to facilitate the nuclear export of eIF1A, consequently regulating endosperm development at the translational level.
Importantly, both DDK1 and eIF1A are conserved among various plant species, implying the preservation of this regulatory module across diverse plants.
Funder
Chinese Academy of Sciences
National Natural Science Foundation of China