Structural Basis of Egg Coat-Sperm Recognition at Fertilization

Isha Raj (1, 2) , Hamed Sadat Al Hosseini (1, 2) , Elisa Dioguardi (1, 2) , Kaoru Nishimura (1, 2) , Ling Han (1, 2) , Alessandra Villa (1, 2) , Daniele de Sanctis (3) , Luca Jovine (1, 2)

1 Karolinska Inst, Ctr Innovat Med, SE-14183 Huddinge, Sweden
2 Karolinska Inst, Dept Biosci & Nutr, SE-14183 Huddinge, Sweden
3 ESRF - European Synchrotron Radiation Facility

Recognition between sperm and the egg surface marks the beginning of life in all sexually reproducing organisms. This fundamental biological event depends on the species-specific interaction between rapidly evolving counterpart molecules on the gametes. We report biochemical, crystallographic, and mutational studies of domain repeats 1-3 of invertebrate egg coat protein VERL and their interaction with cognate sperm protein lysin. VERL repeats fold like the functionally essential N-terminal repeat of mammalian sperm receptor ZP2, whose structure is also described here. Whereas sequence-divergent repeat 1 does not bind lysin, repeat 3 binds it non-species specifically via a high-affinity, largely hydrophobic interface. Due to its intermediate binding affinity, repeat 2 selectively interacts with lysin from the same species. Exposure of a highly positively charged surface of VERL-bound lysin suggests that complex formation both disrupts the organization of egg coat filaments and triggers their electrostatic repulsion, thereby opening a hole for sperm penetration and fusion

Domaines: Sciences du Vivant [q-bio]

Isha Raj, Hamed Sadat Al Hosseini, Elisa Dioguardi, Kaoru Nishimura, Ling Han, et al.. Structural Basis of Egg Coat-Sperm Recognition at Fertilization. Cell, 2017, 169 (7), pp.1315-+. ⟨10.1016/j.cell.2017.05.033⟩. ⟨hal-01691797⟩