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Issue 33, 2014
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Dissection of the structure-forming activity from the structure-guiding activity of silicatein: a biomimetic molecular approach to print optical fibers

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Abstract

Silicateins, a group of proteins forming the proteinaceous axial filaments of the inorganic biosilica spicules of the siliceous sponges, are unique in their dual function to exhibit both structure-guiding (providing the structural platform for the biosilica product) and structure-forming activities (enzymatic function: biosilica synthesis from ortho-silicate). The primary translation product of the silicatein gene comprises a signal peptide, a pro-peptide and, separated by an autocatalytic cleavage site glutamine/aspartic acid [Q/D], the sequence of the mature silicatein protein. In order to dissect the biocatalytic, structure-forming activity of silicatein from its structure-guiding function, two mutated genes were constructed based on the silicatein-α gene of the demosponge Suberites domuncula. (i) A gene encoding for a non-processed silicatein that was mutated, by replacing Q/D [Gln (Q)/Asp (D)] by Q/Q, at the cleavage site within the primary translation product between the pro-peptide and the mature enzyme of wild type silicatein. (ii) A gene encoding for a mature enzymatically-active silicatein in which the S-stretch was replaced by a Q-stretch. The enzymatic activity of the mutated protein was significantly enhanced in the presence of the sponge-specific silicatein-interacting protein, silintaphin-1. The two recombinant proteins were applied for micro-contact printing. Using this technique, parallel layers (diameter 10 μm) of the enzymatically inactive, non-processed silicatein were printed onto a gold surface and used as a structure-guiding template for coating with the soluble enzymatically active silicatein. The experiments revealed that after enzymatic reaction with an ortho-silicate substrate a biosilica mantle is formed that can act as a light waveguide.

Graphical abstract: Dissection of the structure-forming activity from the structure-guiding activity of silicatein: a biomimetic molecular approach to print optical fibers

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Publication details

The article was received on 17 May 2014, accepted on 10 Jun 2014 and first published on 11 Jun 2014


Article type: Paper
DOI: 10.1039/C4TB00801D
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J. Mater. Chem. B, 2014,2, 5368-5377

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    Dissection of the structure-forming activity from the structure-guiding activity of silicatein: a biomimetic molecular approach to print optical fibers

    W. E. G. Müller, T. Link, H. C. Schröder, M. Korzhev, M. Neufurth, D. Brandt and X. Wang, J. Mater. Chem. B, 2014, 2, 5368
    DOI: 10.1039/C4TB00801D

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