How does osteocalcin lacking γ-glutamic groups affect biomimetic apatite formation and what can we say about its structure in mineral-bound form?
- Resource Type
- Article
- Authors
- Iline-Vul, Taly; Kulpanovich, Alexey; Nadav-Tsubery, Merav; Semionov, Artyom; Keinan-Adamsky, Keren; Goobes, Gil
- Source
- Journal of Structural Biology. Aug2019, Vol. 207 Issue 2, p104-114. 11p.
- Subject
- *CYTOSKELETAL proteins
*PHOSPHATE minerals
*APATITE
*MINERALS
*POST-translational modification
*OSTEOCALCIN
*HYDROXYAPATITE
- Language
- ISSN
- 1047-8477
• Bone mimetic apatite was crystallized with osteocalcin lacking γ-carboxylates. • Unmodified OC induces formation of highly ordered hydroxyapatite crystals. • Unmodified OC minimizes the formation of an amorphous phase on the crystallites. • Contacts between protein carbons and phosphates in the mineral were not found. • Apatite bound osteocalcin is in helix bundle form, like the free carboxylated form. Non-collagenous proteins such as osteocalcin function as regulators of the mineralization process in bone. Osteocalcin undergoes post-translational modification adding an extra carboxylate group on three of its glutamate residues to enhance interaction with bone mineral. In this work, we examine regulation of biomimetic apatite formation by osteocalcin that was not modified after translation. We analyze the structural features in the protein and mineral-protein interfaces to elicit the unmodified protein's fold inside the mineral and to unveil the species that interact with the mineral surface. The results presented here give clues on the protein's active role in controlling the mineral phases that are formed on hydroxyapatite crystals and its ability to influence the extent of order in these crystals. [ABSTRACT FROM AUTHOR]