Nacre protein fragment templates lamellar aragonite growth.
Proteins play a major role in the formation of all biominerals. In mollusk shell nacre, complex mixtures and assemblies of proteins and polysaccharides were shown to induce aragonite formation, rather than the thermodynamically favored calcite (both aragonite and calcite are CaCO(3) polymorphs). Here we used N16N, a single 30 amino acid-protein fragment originally inspired by the mineral binding site of N16, a protein in the nacre layer of the Japanese pearl oysters (Pinctada fucata). In a calcite growth solution this short peptide induces in vitro biomineralization. This model biomineral was analyzed using X-ray PhotoElectron Emission spectroMicroscopy (X-PEEM) and found to be strikingly similar to natural nacre: lamellar aragonite with interspersed N16N layers. This and other findings combined suggest a hypothetical scenario in which in vivo three proteins (N16, Pif80, and Pif97) and a polysaccharide (chitin) work in concert to form lamellar nacre.
Metzler
Rebecca A
RA
Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA.
Evans
John Spencer
JS
Killian
Christopher E
CE
Zhou
Dong
D
Churchill
Tyler H
TH
Appathurai
Narayana P
NP
Coppersmith
Susan N
SN
Gilbert
P U P A
PU
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D049911:Pinctada; D017434:Protein Structure, Tertiary
D010446:Peptide Fragments; D002119:Calcium Carbonate