Download MendeleyA Methionine-Rich Repeat Forms a Spiral Conformation That Guides Aragonite Nanofiber Organization in Molluscan Ligaments.
Futagawa, K., Meguro, H., Nagata, K., Ikeya, T., Ito, Y., Suzuki, M.(2025) Biomacromolecules 26: 6667-6683
- PubMed: 40879455 Search on PubMed
- DOI: https://doi.org/10.1021/acs.biomac.5c00916
- Primary Citation Related Structures:
9L1M - PubMed Abstract:
The hinge ligament of Pinctadafucata contains aragonite nanofibers embedded in a dense organic matrix primarily composed of ligament methionine (Met)-rich protein (LMP). LMP features a low-complexity region with 30 repeats of the Met-Met-Met-lysine-proline-aspartic acid (MMMKPD) sequence; however, its structural and functional roles remain unclear. Using synthetic peptides and solution nuclear magnetic resonance with dispersive aragonite particles, we observed that the MMMKPD repeat formed a unique spiral conformation distinct from canonical secondary structures, which was supported by AlphaFold predictions. This structure is stabilized by Met-driven hydrophobic interactions and facilitates the electrostatic alignment of the charged side chains for mineral binding. The spiral structure may represent a previously unrecognized structural motif adapted to mechanically dynamic or high-pressure environments, such as hinge ligaments. Our findings suggest a structural mechanism through which LMP directs aragonite nanofiber formation in molluscan biominerals.
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Organizational Affiliation:
