Model peptide studies of sequence regions in the elastomeric biomineralization protein, Lustrin A. I. The C-domain consensus-PG-, -NVNCT-motif

Bo Zhang, Brandon A. Wustman, Daniel Morse, John Spencer Evans

Research output: Contribution to journalArticle

Abstract

The lustrin superfamily represents a unique group of biomineralization proteins localized between layered aragonite mineral plates (i.e., nacre layer) in mollusk shell. Recent atomic force microscopy (AFM) pulling studies have demonstrated that the lustrin-containing organic nacre layer in the abalone, Haliotis rufescens, exhibits a typical sawtooth force-extension curve with hysteretic recovery. This force extension behavior is reminiscent of reversible unfolding and refolding in elastomeric proteins such as titin and tenascin. Since secondary structure plays an important role in force-induced protein unfolding and refolding, the question is, What secondary structure(s) exist within the major domains of Lustrin A? Using a model peptide (FPGKN-VNCTSGE) representing the 12-residue consensus sequence found near the N-termini of the first eight cysteine-rich domains (C-domains) within the Lustrin A protein, we employed CD, NMR spectroscopy, and simulated annealing/minimization to determine the secondary structure preferences for this sequence. At pH 7.4, we find that the 12-mer sequence adopts a loop conformation, consisting of a "bend" or "turn" involving residues G3-K4 and N7-C8-T9, with extended conformations arising at F1-G3; K4-V6; T9-S10-G11 in the sequence. Minor pH-dependent conformational effects were noted for this peptide; however, there is no evidence for a salt-bridge interaction between the K4 and E12 side chains. The presence of a loop conformation within the highly conserved -PG-, -NVNCT - sequence of C1-C8 domains may have important structural and mechanistic implications for the Lustrin A protein with regard to elastic behavior.

Original languageEnglish (US)
Pages (from-to)358-369
Number of pages12
JournalBiopolymers
Volume63
Issue number6
DOIs
StatePublished - 2002

Keywords

  • Abalone
  • Aragonite mineral plates
  • Atomic force microscopy
  • Biomineralization proteins
  • Elastomeric proteins
  • Hysteretic recovery
  • Lustrin
  • Mollusk shell
  • Nacre layer
  • Reversible unfolding and refolding
  • Sawtooth force-extension
  • Secondary structure

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry

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