1l3q
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(New page: 200px<br /><applet load="1l3q" size="450" color="white" frame="true" align="right" spinBox="true" caption="1l3q" /> '''H. rufescens abalone shell Lustrin A consens...)
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Revision as of 00:19, 25 November 2007
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H. rufescens abalone shell Lustrin A consensus repeat, FPGKNVNCTSGE, pH 7.4, 1-H NMR structure
Overview
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 (FPGKNVNCTSGE) 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.
About this Structure
1L3Q is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Model peptide studies of sequence regions in the elastomeric biomineralization protein, Lustrin A. I. The C-domain consensus-PG-, -NVNCT-motif., Zhang B, Wustman BA, Morse D, Evans JS, Biopolymers. 2002 May;63(6):358-69. PMID:11920437
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