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Cell. 2017 Jun 15;169(7):1315-1326.e17. doi: 10.1016/j.cell.2017.05.033.

Structural Basis of Egg Coat-Sperm Recognition at Fertilization.

Author information

1
Department of Biosciences and Nutrition and Center for Innovative Medicine, Karolinska Institutet, Huddinge, SE-141 83, Sweden.
2
ESRF - The European Synchrotron Radiation Facility, Grenoble 38000, France.
3
Department of Biosciences and Nutrition and Center for Innovative Medicine, Karolinska Institutet, Huddinge, SE-141 83, Sweden. Electronic address: luca.jovine@ki.se.

Abstract

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.

KEYWORDS:

X-ray crystallography; biological evolution; fertilization; protein interaction domains and motifs; sperm-ovum interactions; zona pellucida; zona pellucida glycoproteins

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PMID:
28622512
PMCID:
PMC5480393
DOI:
10.1016/j.cell.2017.05.033
[Indexed for MEDLINE]
Free PMC Article

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