title: Crystal structure of ovocleidin-17, a major protein of the calcified Gallus gallus eggshell: implications in the calcite mineral growth pattern.
abstract: Ovocleidin-17 (OC17) from Gallus gallus is one of the best candidates to control and regulate the deposition of calcium carbonate in the calcified eggshell layer. Here, the crystal structure of monomeric OC17, determined at a resolution of 1.5 A, was refined to a crystallographic R-factor of 20.1%. This is the first protein directly involved in a non-pathological biomineralization process resolved by x-ray diffraction to date. The protein has a mixed alpha/beta structure containing a single C-type lectin-like domain. However, although OC17 shares the conserved scaffold of the C-type lectins, it does not bind carbohydrates. Nevertheless, in vitro OC17 modifies the crystalline habit of calcium carbonate (CaCO3) and the pattern of crystal growth at intervals of 5-200 microg/ml. Determining the three-dimensional structure of OC17 contributes to a better understanding of the biological behavior of structurally related biomolecules and of the mechanisms involved in eggshell and other mineralization processes.
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México (UNAM) Circuito Exterior, C.U. México, D.F. 04510, Mexico.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Reyes-Grajeda
authors.forename: Abel
authors.initials: A
authors.lastname: Moreno
authors.forename: Antonio
authors.initials: A
authors.lastname: Romero
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002119:Calcium Carbonate / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry; D002645:Chickens; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D004527:Egg Proteins / Q000737:chemistry*; D004528:Egg Shell / Q000737:chemistry*; D037102:Lectins / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D014961:X-Ray Diffraction
chemical_list: D002241:Carbohydrates; D004527:Egg Proteins; D037102:Lectins; C095273:ovocleidin 17; D002119:Calcium Carbonate; D003545:Cysteine