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Conservation of folding and association within a family of spidroin N-terminal domains

Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to w...

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Autores principales: Heiby, Julia C., Rajab, Suhaila, Rat, Charlotte, Johnson, Christopher M., Neuweiler, Hannes
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5711802/
https://www.ncbi.nlm.nih.gov/pubmed/29196631
http://dx.doi.org/10.1038/s41598-017-16881-6
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author Heiby, Julia C.
Rajab, Suhaila
Rat, Charlotte
Johnson, Christopher M.
Neuweiler, Hannes
author_facet Heiby, Julia C.
Rajab, Suhaila
Rat, Charlotte
Johnson, Christopher M.
Neuweiler, Hannes
author_sort Heiby, Julia C.
collection PubMed
description Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to which forces of self-assembly is conserved across spider glands and species is currently unknown because quantitative measures are missing. Here, we report the comparative investigation of spidroin NTDs originating from the major ampullate glands of the spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus. We characterized equilibrium thermodynamics and kinetics of folding and self-association using dynamic light scattering, stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. We found cooperative two-state folding on a sub-millisecond time scale through a late transition state of all four domains. Stability was compromised by repulsive electrostatic forces originating from clustering of point charges on the NTD surface required for function. pH-driven dimerization proceeded with characteristic fast kinetics yielding high affinities. Results showed that energetics and kinetics of NTD self-assembly are highly conserved across spider species despite the different silk mechanical properties and web geometries they produce.
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spelling pubmed-57118022017-12-06 Conservation of folding and association within a family of spidroin N-terminal domains Heiby, Julia C. Rajab, Suhaila Rat, Charlotte Johnson, Christopher M. Neuweiler, Hannes Sci Rep Article Web spiders synthesize silk fibres, nature’s toughest biomaterial, through the controlled assembly of fibroin proteins, so-called spidroins. The highly conserved spidroin N-terminal domain (NTD) is a pH-driven self-assembly device that connects spidroins to super-molecules in fibres. The degree to which forces of self-assembly is conserved across spider glands and species is currently unknown because quantitative measures are missing. Here, we report the comparative investigation of spidroin NTDs originating from the major ampullate glands of the spider species Euprosthenops australis, Nephila clavipes, Latrodectus hesperus, and Latrodectus geometricus. We characterized equilibrium thermodynamics and kinetics of folding and self-association using dynamic light scattering, stopped-flow fluorescence and circular dichroism spectroscopy in combination with thermal and chemical denaturation experiments. We found cooperative two-state folding on a sub-millisecond time scale through a late transition state of all four domains. Stability was compromised by repulsive electrostatic forces originating from clustering of point charges on the NTD surface required for function. pH-driven dimerization proceeded with characteristic fast kinetics yielding high affinities. Results showed that energetics and kinetics of NTD self-assembly are highly conserved across spider species despite the different silk mechanical properties and web geometries they produce. Nature Publishing Group UK 2017-12-01 /pmc/articles/PMC5711802/ /pubmed/29196631 http://dx.doi.org/10.1038/s41598-017-16881-6 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Heiby, Julia C.
Rajab, Suhaila
Rat, Charlotte
Johnson, Christopher M.
Neuweiler, Hannes
Conservation of folding and association within a family of spidroin N-terminal domains
title Conservation of folding and association within a family of spidroin N-terminal domains
title_full Conservation of folding and association within a family of spidroin N-terminal domains
title_fullStr Conservation of folding and association within a family of spidroin N-terminal domains
title_full_unstemmed Conservation of folding and association within a family of spidroin N-terminal domains
title_short Conservation of folding and association within a family of spidroin N-terminal domains
title_sort conservation of folding and association within a family of spidroin n-terminal domains
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5711802/
https://www.ncbi.nlm.nih.gov/pubmed/29196631
http://dx.doi.org/10.1038/s41598-017-16881-6
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