Modulation of biomineralization morphology by phosphorylated collagen peptides: insights into osteogenesis imperfecta pathophysiology.

Osteogenesis imperfecta (OI) is a hereditary skeletal disorder characterized by bone fragility and deformities, primarily attributed to defects in type I collagen, the most abundant structural protein in humans. Multiple phosphorylation sites have been detected within collagen, suggesting that phosphorylation may influence mineralization processes, thereby impacting the development of OI. In this study, we investigated the modulation of biomineralization morphology by phosphorylated collagen peptides mimicking Gly-Ser mutations in osteogenesis imperfecta. A series of collagen peptide sequences, including GPO₁₃S, GPO₁₃pS, GPO₁₂S, GPO₁₂pS, GPO₁₁S, and GPO₁₁pS, were synthesized to explore the role of phosphorylation in peptide stability and its templating effect on biomineralization. The CD results indicated that the phosphorylation of Gly-pSer mutants reduces the stability of collagen peptides. SEM images revealed that phosphorylated peptides acted as templates, guiding the morphology of calcium carbonate into either olive-like or spherical structures, depending on their conformational state of the peptides. Non-phosphorylated peptides maintained a calcite crystal structure. The XRD patterns predominantly exhibited peaks associated with calcite and vaterite for GPO₁₃pS-CaCO₃, GPO₁₂pS-CaCO₃, and GPO₁₁pS-CaCO₃, and peaks associated with calcite for GPO₁₃S-CaCO₃, GPO₁₂S-CaCO₃, and GPO₁₁S-CaCO₃, indicating a transformation of mesocrystals influenced by peptide phosphorylation. Our findings elucidate the crucial role of phosphorylated collagen peptides in mediating biomineralization morphology and polymorph selection, offering insights into the complex pathophysiology of OI.