Poster abstracts
Poster number 7 submitted by Aaron Bruns
SnRK1 phosphorylates eIF4E/iso4E to regulate translation
Aaron N. Bruns (OSU), Sizhun Li (OSU), David M. Bisaro (OSU)
Abstract:
Plant SNF1-related kinase (SnRK1) belongs to a conserved family that includes animal AMP-activated protein kinase (AMPK) and yeast SNF1. These serine/threonine kinases sense the AMP:ATP ratio in cells and play key roles in maintaining energy homeostasis through a variety of pathways. SnRK1/SNF1/AMPK are also involved in both biotic and abiotic stress responses. Our lab previously identified SnRK1 as a target of suppression by geminivirus pathogenicity factors, and found that SnRK1 overexpression provides resistance to infection by the DNA containing geminiviruses as well as RNA viruses. However, the mechanism underlying this resistance remained unclear. In these studies, we demonstrate the presence of a previously unknown regulatory pathway in which SnRK1 interacts with and phosphorylates the mRNA cap-binding protein Eukaryotic Initiation Factor 4E (eIF4E) and its isoform (eIFiso4E). Additionally, we show that this inhibits translation in both yeast and plant (Nicotiana benthamiana) cells. These observations provide a direct link between a cellular energy sensing kinase and translation control, and likely also explain the virus resistance phenotype observed in SnRK1 overexpressing N. benthamiana. SnRK1 and eIF4E/iso4E are deeply conserved in plants, and SnRK1/SNF1/AMPK phosphorylation sites are also conserved in plant, fungal (e.g. Saccharomyces cerevisiae) and invertebrate animal (e.g. Drosophila melanogaster and Caenorhabditis elegans) eIF4E. Therefore, this novel regulatory mechanism may have broad importance in pathogen defense and stress response in many organisms, including valuable crop plants and potentially a wide variety of other non-vertebrate systems.
Keywords: Translation, eIF4E, AMPK SnRK1 SNF1