Structural assembly of the subcortical maternal complex SCMC

Area of Science:

• Structural Biology
• Developmental Biology
• Genetics

Background:

• The subcortical maternal complex (SCMC) is crucial for mammalian preimplantation development.
• Understanding how the SCMC core interacts with regulatory partners is essential but remains unclear.

Purpose of the Study:

• To determine the cryo-electron microscopy (cryo-EM) structures of mouse and human SCMC bound to regulatory partners.
• To elucidate the molecular mechanisms underlying SCMC complex assembly and its interactions with ZBED3, NLRP2, and NLRP7.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to determine high-resolution structures.
• In vivo proximity ligation assays and in vitro pull-down assays for cross-validation.

Main Results:

• Determined structures of mouse SCMC with ZBED3 and human SCMC with NLRP2.
• ZBED3 interacts with all SCMC core subunits (MATER/NLRP5, TLE6, FLOPED/OOEP) via its zinc finger domain.
• NLRP2 and NLRP7 bind to TLE6 through specific domain interactions (LRR and WD40 domains).

Conclusions:

• Proposes a 'Lego-like' assembly model for SCMC complex formation.
• Highlights diverse molecular interfaces for SCMC core recruitment of regulatory partners.
• Provides critical structural insights into SCMC architecture and its roles in early mammalian embryogenesis.