Evidence for vitellogenin DNA-binding in honey bees

DNA-binding proteins play essential roles in DNA replication, DNA repair, DNA organization, and several aspects of gene regulation. Their well-studied structures and charge configurations aid in identifying similar functions in other proteins. Vitellogenin (Vg) is a highly conserved protein that is central to egg-yolk formation in most animal taxa. The protein is largely viewed as a transporter, but effects on immunity and behavior are documented. Experiments in honey bees (Apis mellifera) additionally suggest a role in gene regulation. The possibility of Vg-DNA binding has broad relevance due to Vg being phylogenetically widespread and having descendant proteins relevant to human cardiovascular health. Previously, we found that a Vg subunit can translocate to the honey bee nucleus and interact with DNA. Now, we provide a structural explanation for Vg's DNA-binding potential by identifying conserved DNA-binding amino acids in structural regions similar to established DNA-binding proteins. Next, we examined how Vg-DNA binding may elicit gene expression changes in honey bee workers, characterized by distinct changes in Vg levels over their lifetimes. Finally, we identify other nuclear proteins likely bound to the Vg-DNA complex in honey bees. Our data suggest that Vg-DNA binding is associated with expression changes in dozens of genes and that the Vg-DNA complex interacts with dozens more nuclear proteins. We propose that Vg-DNA binding can regulate several important processes in honey bee workers, including energy metabolism, behavior, and signaling. Due to the conserved nature of Vg and its descendant proteins, these functions may be present in various animals, including humans.