CBD-1 organizes two independent complexes required for eggshell vitelline layer formation and egg activation in C. elegans

Developmental biology

Delfina P. González^1¹  Helen V. Lamb^1² 

[1] Department of Biology and Program in Molecular Biology, Pomona College, Claremont, CA 91711, USA^1;Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA^2

关键词: CBD;    chitin-binding domain;    CHS;    chitin synthase;    co-IP;    co-immunoprecipitation;    CPG;    chondroitin proteoglycan;    dsRNA;    double-stranded RNA;    EGG;    egg sterile;    MBK;    mini-brain kinase;    PERM;    permeable eggshell;    RNAi;    RNA interference;    SEC;    self-excising cassette;    SQV;    squashed vulva;    ZPD;    zona pellucida domain;    Vitelline layer;    C. elegans eggshell;    Fertilization;    PERM-2 and PERM-4;    CBD-1;    Zona pellucida;   

DOI  :  10.1016/j.ydbio.2018.08.005

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Metazoan eggs have a specialized coat of extracellular matrix that aids in sperm-egg recognition. The coat is rapidly remodeled after fertilization to prevent polyspermy and establish a more permanent barrier to protect the developing embryo. In nematodes, this coat is called the vitelline layer, which is remodeled into the outermost layer of a rigid and impermeable eggshell. We have identified three key components of the vitelline layer structural scaffold – PERM-2, PERM-4 and CBD-1, the first such proteins to be described in the nematode C. elegans. CBD-1 tethered PERM-2 and PERM-4 to the nascent vitelline layer via two N-terminal chitin-binding domains. After fertilization, all three proteins redistributed from the zygote surface to the outer eggshell. Depletion of PERM-2 and PERM-4 from the scaffold led to a porous vitelline layer that permitted soluble factors to leak through the eggshell and resulted in embryonic death. In addition to its role in vitelline layer assembly, CBD-1 is also known to anchor a protein complex required for fertilization and egg activation (EGG-1-5/CHS-1/MBK-2). We found the PERM complex and EGG complex to be functionally independent, and structurally organized through distinct domains of CBD-1. CBD-1 is thus a multifaceted regulator that promotes distinct aspects of vitelline layer assembly and egg activation. In sum, our findings characterize the first vitelline layer components in nematodes, and provide a foundation through which to explore both conserved and species-specific strategies used by animals to build protective barriers following fertilization.

【 授权许可】

CC BY