Nanolattice-Forming Hybrid Collagens in Protective Shark Egg Cases

Area of Science:

• Materials Science
• Biomaterials Engineering
• Structural Biology

Background:

• Achieving long-range, ordered nanostructures is a significant challenge in nanomaterial fabrication.
• Elasmobranch egg cases exhibit hierarchical nanolattices, demonstrating natural nanoscale self-assembly.
• The protein precursors and their sequences involved in forming these nanolattices were previously unknown.

Purpose of the Study:

• To identify the protein sequences responsible for the nanolattice structure in elasmobranch egg cases.
• To understand the molecular self-assembly mechanisms underlying natural nanostructure formation.
• To explore potential applications in designing novel protein-based nanomaterials.

Main Methods:

• RNA sequencing (RNA-seq) and proteomic techniques were employed to identify nanolattice-forming proteins.
• Mass spectrometry was used to elucidate the identity and role of cross-links.
• In situ small-angle X-ray scattering (SAXS) provided insights into structural organization.

Main Results:

• A cohort of nanolattice-forming proteins was identified, characterized by a collagenous midblock and flanking domains.
• Homologous proteins were found in other cartilaginous fishes, indicating a conserved self-assembly strategy.
• The stabilizing role of specific cross-links in the nanolattice structure was determined.

Conclusions:

• The study reveals the molecular basis of nanolattice formation in elasmobranch egg cases.
• Findings suggest a conserved, evolutionarily ancient mechanism for nanoscale self-assembly.
• This research provides a foundation for designing protein-based liquid crystalline elastomers and self-assembling nanolattices.