Structural features that distinguish kinetically distinct biomineralization polypeptides

Sebastiano Collino, John Evans

Research output: Contribution to journalArticle

Abstract

AP7 and AP24 are mollusk shell proteins which are responsible for aragonite polymorph formation and stabilization within the nacre layer of the Pacific red abalone, Haliotis rufescens. It is known that the 30-AA N-terminal. mineral modification domains of both proteins (AP7N, AP24N) possess identical multifunctional mineralization capabilities within in vitro assays but differ in terms of rate kinetics, with AP24N > AP7N. In this report, we identify previously unreported molecular features of AP24N and contrast the lowest energy polypeptide backbone structures of AP24N (planar configuration) with that of AP7N ("bent paper clip" configuration) using NMR data and simulated annealing molecular dynamics structure refinement. Like AP7N, we find that AP24N possesses an unfolded conformation, can sequester Ca(II) and other multivalent metal ions, can adsorb onto or within calcite crystals, and possesses anionic and cationic electrostatic "pocket" regions on its molecular surfaces. However, AP24N has some unique features: greater conformational responsiveness to Ca(II), the tendency to form a more planar backbone configuration, and longer anionic and hydrogen-bonding donor/acceptor sequence blocks. We conclude that the presence of unfolded polypeptide conformation, electrostatic surface pockets, and interactive sequence clustering endow both AP7N and AP24N with similar features that lead to comparable effects on crystal morphology and nucleation. However, AP24N possesses longer anionic and hydrogen-bonding sequence clusters and exhibits a tendency to adopt a more planar backbone configuration than AP7N does. We believe that these features facilitate peptide-mineral, peptide-ion, or water cluster interactions, thereby enhancing the mineralization kinetics of AP24N over AP7N.

Original languageEnglish (US)
Pages (from-to)1686-1694
Number of pages9
JournalBiomacromolecules
Volume8
Issue number5
DOIs
StatePublished - May 2007

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Biomineralization
Polypeptides
Peptides
Conformations
Electrostatics
Hydrogen bonds
Minerals
Proteins
Crystals
Kinetics
Calcium Carbonate
Calcite
Hydrogen Bonding
Simulated annealing
Polymorphism
Static Electricity
Metal ions
Molecular dynamics
Assays
Nacre

ASJC Scopus subject areas

  • Organic Chemistry
  • Biochemistry, Genetics and Molecular Biology(all)
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Structural features that distinguish kinetically distinct biomineralization polypeptides. / Collino, Sebastiano; Evans, John.

In: Biomacromolecules, Vol. 8, No. 5, 05.2007, p. 1686-1694.

Research output: Contribution to journalArticle

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