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Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion

The past decade has seen a fundamental reappraisal of the protein structure-to-function paradigm because it became evident that a significant fraction of polypeptides are lacking ordered structures under physiological conditions. Ligand-induced disorder-to-order transition plays a key role in the bi...

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Autores principales: Sotomayor-Pérez, Ana-Cristina, Ladant, Daniel, Chenal, Alexandre
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303809/
https://www.ncbi.nlm.nih.gov/pubmed/25559101
http://dx.doi.org/10.3390/toxins7010001
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author Sotomayor-Pérez, Ana-Cristina
Ladant, Daniel
Chenal, Alexandre
author_facet Sotomayor-Pérez, Ana-Cristina
Ladant, Daniel
Chenal, Alexandre
author_sort Sotomayor-Pérez, Ana-Cristina
collection PubMed
description The past decade has seen a fundamental reappraisal of the protein structure-to-function paradigm because it became evident that a significant fraction of polypeptides are lacking ordered structures under physiological conditions. Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by RTX (Repeat in ToXin) motifs found in more than 250 virulence factors secreted by Gram-negative pathogenic bacteria. We have investigated several RTX-containing polypeptides of different lengths, all derived from the Bordetella pertussis adenylate cyclase toxin, CyaA. Using a combination of experimental approaches, we showed that the RTX proteins exhibit the hallmarks of intrinsically disordered proteins in the absence of calcium. This intrinsic disorder mainly results from internal electrostatic repulsions between negatively charged residues of the RTX motifs. Calcium binding triggers a strong reduction of the mean net charge, dehydration and compaction, folding and stabilization of secondary and tertiary structures of the RTX proteins. We propose that the intrinsically disordered character of the RTX proteins may facilitate the uptake and secretion of virulence factors through the bacterial secretion machinery. These results support the hypothesis that the folding reaction is achieved upon protein secretion and, in the case of proteins containing RTX motifs, could be finely regulated by the calcium gradient across bacterial cell wall.
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spelling pubmed-43038092015-02-02 Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion Sotomayor-Pérez, Ana-Cristina Ladant, Daniel Chenal, Alexandre Toxins (Basel) Review The past decade has seen a fundamental reappraisal of the protein structure-to-function paradigm because it became evident that a significant fraction of polypeptides are lacking ordered structures under physiological conditions. Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by RTX (Repeat in ToXin) motifs found in more than 250 virulence factors secreted by Gram-negative pathogenic bacteria. We have investigated several RTX-containing polypeptides of different lengths, all derived from the Bordetella pertussis adenylate cyclase toxin, CyaA. Using a combination of experimental approaches, we showed that the RTX proteins exhibit the hallmarks of intrinsically disordered proteins in the absence of calcium. This intrinsic disorder mainly results from internal electrostatic repulsions between negatively charged residues of the RTX motifs. Calcium binding triggers a strong reduction of the mean net charge, dehydration and compaction, folding and stabilization of secondary and tertiary structures of the RTX proteins. We propose that the intrinsically disordered character of the RTX proteins may facilitate the uptake and secretion of virulence factors through the bacterial secretion machinery. These results support the hypothesis that the folding reaction is achieved upon protein secretion and, in the case of proteins containing RTX motifs, could be finely regulated by the calcium gradient across bacterial cell wall. MDPI 2014-12-31 /pmc/articles/PMC4303809/ /pubmed/25559101 http://dx.doi.org/10.3390/toxins7010001 Text en © 2014 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Review
Sotomayor-Pérez, Ana-Cristina
Ladant, Daniel
Chenal, Alexandre
Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title_full Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title_fullStr Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title_full_unstemmed Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title_short Disorder-to-Order Transition in the CyaA Toxin RTX Domain: Implications for Toxin Secretion
title_sort disorder-to-order transition in the cyaa toxin rtx domain: implications for toxin secretion
topic Review
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303809/
https://www.ncbi.nlm.nih.gov/pubmed/25559101
http://dx.doi.org/10.3390/toxins7010001
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