title: Fertilization competence of the egg-coating envelope is regulated by direct interaction of dicalcin and gp41, the Xenopus laevis ZP3.
abstract: Fertilization begins with species-restricted interaction of sperm and the egg-coating envelope, which includes a three-dimensional meshwork of filaments composed of glycoproteins (called ZP proteins). Growing evidence has unveiled the molecular nature of ZP proteins; however, the structural property conferring fertilization competence to the egg-coating envelope remains unknown. Here, we show the molecular mechanism that mediates direct interaction between dicalcin, a novel fertilization-suppressive ZP protein-associated protein, and gp41, a Xenopus laevis ortholog of mammalian ZP3, and subsequently demonstrate the structural basis of the envelope for fertilization competence. The interactive regions between dicalcin and gp41 comprised five and nine amino acid residues within dicalcin and twenty-three within gp41 [corrected]. Synthetic peptides corresponding to these regions dramatically affected fertilization: treatment with dicalcin- or gp41-derived peptides decreased or increased fertilization rates, respectively. Prior application of these peptides caused distinct alterations in the in vivo lectin-staining pattern of the envelope as well. Transmission electron microscopy analysis revealed that the dicalcin-derived peptide induced the formation of a well-organized meshwork, whereas the gp41-derived peptide caused the formation of a significantly disorganized meshwork. These findings indicated that the fertilization competence of the egg-coating envelope is crucially regulated by the direct interaction between dicalcin and gp41.
authors.affiliation: Department of Physiology, School of Medicine, Toho University, Ohmori-nishi 5-21-16, Ohta-ku, Tokyo 143-8540, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Miwa
authors.affiliation: Department of Anatomy, School of Medicine, Kitasato University, Kitasato 1-15-1, Minami-ku, Sagamihara, Kanagawa 228-8555, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Ogawa
authors.affiliation: Department of Physiology, School of Medicine, Toho University, Ohmori-nishi 5-21-16, Ohta-ku, Tokyo 143-8540, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Hanaue
authors.affiliation: Department of Physiology, School of Medicine, Toho University, Ohmori-nishi 5-21-16, Ohta-ku, Tokyo 143-8540, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takamatsu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D005306:Fertilization; D006023:Glycoproteins / Q000737:chemistry / Q000502:physiology*; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010063:Ovum / Q000502:physiology / Q000648:ultrastructure; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D009418:S100 Proteins / Q000737:chemistry / Q000502:physiology*; D013084:Sperm-Ovum Interactions; D029867:Xenopus Proteins / Q000737:chemistry / Q000502:physiology*; D014982:Xenopus laevis / Q000502:physiology*
chemical_list: D006023:Glycoproteins; D010446:Peptide Fragments; D009418:S100 Proteins; C525113:S100A11 protein, Xenopus; D029867:Xenopus Proteins; C000608780:zona pellucida protein 3, Xenopus