Investigating domain function and protein interactions of the ELMOD family proteins involved in pollen aperture formation in Arabidopsis

Abstract

In flowering plants, the ancient eukaryotic Engulfment and Motility Domain (ELMOD) genes play a role in the formation of pollen apertures. Apertures are hole-like structures on the pollen surface that develop at distinct plasma membrane domains and lack pollen wall exine. Apertures are conserved within a plant species, yet quite diverse across species. Openings provided by the apertures can allow pollen tubes that carry sperm cells to exit from pollen grains and, in some plant species, loss of apertures leads to male sterility. Two of the Arabidopsis thaliana ELMOD proteins–ELMOD_B (also known as MCR) and ELMOD_A–control the number of apertures while a third protein, ELMOD_E, causes changes in aperture shape when mis-expressed in developing pollen. However, the biochemical function of ELMOD proteins in plants has yet to be deciphered. We have investigated the importance of the ELMOD protein domains by deleting and swapping domains of the ELMOD genes. We demonstrate that 1) all three protein domains in the Arabidopsis ELMODs are essential for these proteins’ function; 2) the C-terminus and the putative GAP region are important for nuclear enrichment; and 3) the N-terminus of ELMOD_E is responsible for its distinct effect on aperture formation while the N-terminus of MCR is important for its function. To identify interactors of the ELMOD proteins, we have also performed protein-protein interaction assays. So far, these assays have discovered weak protein interactions and suggested that plant ELMOD proteins may have biochemical activity different from their mammalian counterparts.Thomas Byers Memorial Scholarship, Ohio State University Department of Molecular GeneticsNSF grant MCB-1817836NSF grant MCB-2240972A five-year embargo was granted for this item.Academic Major: Molecular Genetic