title: Synergistic Biomineralization Phenomena Created by a Combinatorial Nacre Protein Model System.
abstract: In the nacre or aragonite layer of the mollusk shell, proteomes that regulate both the early stages of nucleation and nano-to-mesoscale assembly of nacre tablets from mineral nanoparticle precursors exist. Several approaches have been developed to understand protein-associated mechanisms of nacre formation, yet we still lack insight into how protein ensembles or proteomes manage nucleation and crystal growth. To provide additional insights, we have created a proportionally defined combinatorial model consisting of two nacre-associated proteins, C-RING AP7 (shell nacre, Haliotis rufescens) and pseudo-EF hand PFMG1 (oyster pearl nacre, Pinctada fucata), whose individual in vitro mineralization functionalities are well-documented and distinct from one another. Using scanning electron microscopy, flow cell scanning transmission electron microscopy, atomic force microscopy, Ca(II) potentiometric titrations, and quartz crystal microbalance with dissipation monitoring quantitative analyses, we find that both nacre proteins are functionally active within the same mineralization environments and, at 1:1 molar ratios, synergistically create calcium carbonate mesoscale structures with ordered intracrystalline nanoporosities, extensively prolong nucleation times, and introduce an additional nucleation event. Further, these two proteins jointly create nanoscale protein aggregates or phases that under mineralization conditions further assemble into protein-mineral polymer-induced liquid precursor-like phases with enhanced ACC stabilization capabilities, and there is evidence of intermolecular interactions between AP7 and PFMG1 under these conditions. Thus, a combinatorial model system consisting of more than one defined biomineralization protein dramatically changes the outcome of the in vitro biomineralization process.
authors.affiliation: Center for Skeletal Biology, Laboratory for Chemical Physics, New York University College of Dentistry , New York, New York 10010, United States.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Chang
authors.affiliation: Department of Physics, University of York , Heslington, York, United Kingdom.
authors.forename: Teresa
authors.initials: T
authors.lastname: Roncal-Herrero
authors.affiliation: Department of Electronics, University of York , Heslington, York, United Kingdom.
authors.forename: Tamara
authors.initials: T
authors.lastname: Morgan
authors.affiliation: Department of Electronics, University of York , Heslington, York, United Kingdom.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Dunn
authors.affiliation: Department of Chemistry, Universitat Konstanz , Konstanz, Germany.
authors.forename: Ashit
authors.initials: A
authors.lastname: Rao
authors.affiliation: Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853-1501, United States.
authors.forename: Jennie A M R
authors.initials: JA
authors.lastname: Kunitake
authors.affiliation: Center for Skeletal Biology, Laboratory for Chemical Physics, New York University College of Dentistry , New York, New York 10010, United States.
authors.forename: Susan
authors.initials: S
authors.lastname: Lui
authors.affiliation: Department of Physics, University of York , Heslington, York, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Bilton
authors.affiliation: Department of Materials Science and Engineering, Cornell University , Ithaca, New York 14853-1501, United States.
authors.forename: Lara A
authors.initials: LA
authors.lastname: Estroff
authors.affiliation: Department of Physics, University of York , Heslington, York, United Kingdom.
authors.forename: Roland
authors.initials: R
authors.lastname: Kröger
authors.affiliation: Department of Electronics, University of York , Heslington, York, United Kingdom.
authors.forename: Steven
authors.initials: S
authors.lastname: Johnson
authors.affiliation: Department of Chemistry, Universitat Konstanz , Konstanz, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Cölfen
authors.affiliation: Center for Skeletal Biology, Laboratory for Chemical Physics, New York University College of Dentistry , New York, New York 10010, United States.
authors.forename: John Spencer
authors.initials: JS
authors.lastname: Evans
mesh_terms: D000818:Animals; D003460:Crystallization; D049851:Gastropoda / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D060734:Nacre / Q000032:analysis / Q000378:metabolism*; D049911:Pinctada / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D011506:Proteins / Q000032:analysis / Q000378:metabolism*
chemical_list: D060734:Nacre; D011506:Proteins