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Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core

Critical molecular events that control conformational transitions in most allosteric proteins are ill-defined. The mannose-specific FimH protein of Escherichia coli is a prototypic bacterial adhesin that switches from an ‘inactive’ low-affinity state (LAS) to an ‘active’ high-affinity state (HAS) co...

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Autores principales: Kisiela, Dagmara I., Magala, Pearl, Interlandi, Gianluca, Carlucci, Laura A., Ramos, Angelo, Tchesnokova, Veronika, Basanta, Benjamin, Yarov-Yarovoy, Vladimir, Avagyan, Hovhannes, Hovhannisyan, Anahit, Thomas, Wendy E., Stenkamp, Ronald E., Klevit, Rachel E., Sokurenko, Evgeni V.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064603/
https://www.ncbi.nlm.nih.gov/pubmed/33826682
http://dx.doi.org/10.1371/journal.ppat.1009440
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author Kisiela, Dagmara I.
Magala, Pearl
Interlandi, Gianluca
Carlucci, Laura A.
Ramos, Angelo
Tchesnokova, Veronika
Basanta, Benjamin
Yarov-Yarovoy, Vladimir
Avagyan, Hovhannes
Hovhannisyan, Anahit
Thomas, Wendy E.
Stenkamp, Ronald E.
Klevit, Rachel E.
Sokurenko, Evgeni V.
author_facet Kisiela, Dagmara I.
Magala, Pearl
Interlandi, Gianluca
Carlucci, Laura A.
Ramos, Angelo
Tchesnokova, Veronika
Basanta, Benjamin
Yarov-Yarovoy, Vladimir
Avagyan, Hovhannes
Hovhannisyan, Anahit
Thomas, Wendy E.
Stenkamp, Ronald E.
Klevit, Rachel E.
Sokurenko, Evgeni V.
author_sort Kisiela, Dagmara I.
collection PubMed
description Critical molecular events that control conformational transitions in most allosteric proteins are ill-defined. The mannose-specific FimH protein of Escherichia coli is a prototypic bacterial adhesin that switches from an ‘inactive’ low-affinity state (LAS) to an ‘active’ high-affinity state (HAS) conformation allosterically upon mannose binding and mediates shear-dependent catch bond adhesion. Here we identify a novel type of antibody that acts as a kinetic trap and prevents the transition between conformations in both directions. Disruption of the allosteric transitions significantly slows FimH’s ability to associate with mannose and blocks bacterial adhesion under dynamic conditions. FimH residues critical for antibody binding form a compact epitope that is located away from the mannose-binding pocket and is structurally conserved in both states. A larger antibody-FimH contact area is identified by NMR and contains residues Leu-34 and Val-35 that move between core-buried and surface-exposed orientations in opposing directions during the transition. Replacement of Leu-34 with a charged glutamic acid stabilizes FimH in the LAS conformation and replacement of Val-35 with glutamic acid traps FimH in the HAS conformation. The antibody is unable to trap the conformations if Leu-34 and Val-35 are replaced with a less bulky alanine. We propose that these residues act as molecular toggle switches and that the bound antibody imposes a steric block to their reorientation in either direction, thereby restricting concerted repacking of side chains that must occur to enable the conformational transition. Residues homologous to the FimH toggle switches are highly conserved across a diverse family of fimbrial adhesins. Replacement of predicted switch residues reveals that another E. coli adhesin, galactose-specific FmlH, is allosteric and can shift from an inactive to an active state. Our study shows that allosteric transitions in bacterial adhesins depend on toggle switch residues and that an antibody that blocks the switch effectively disables adhesive protein function.
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spelling pubmed-80646032021-05-04 Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core Kisiela, Dagmara I. Magala, Pearl Interlandi, Gianluca Carlucci, Laura A. Ramos, Angelo Tchesnokova, Veronika Basanta, Benjamin Yarov-Yarovoy, Vladimir Avagyan, Hovhannes Hovhannisyan, Anahit Thomas, Wendy E. Stenkamp, Ronald E. Klevit, Rachel E. Sokurenko, Evgeni V. PLoS Pathog Research Article Critical molecular events that control conformational transitions in most allosteric proteins are ill-defined. The mannose-specific FimH protein of Escherichia coli is a prototypic bacterial adhesin that switches from an ‘inactive’ low-affinity state (LAS) to an ‘active’ high-affinity state (HAS) conformation allosterically upon mannose binding and mediates shear-dependent catch bond adhesion. Here we identify a novel type of antibody that acts as a kinetic trap and prevents the transition between conformations in both directions. Disruption of the allosteric transitions significantly slows FimH’s ability to associate with mannose and blocks bacterial adhesion under dynamic conditions. FimH residues critical for antibody binding form a compact epitope that is located away from the mannose-binding pocket and is structurally conserved in both states. A larger antibody-FimH contact area is identified by NMR and contains residues Leu-34 and Val-35 that move between core-buried and surface-exposed orientations in opposing directions during the transition. Replacement of Leu-34 with a charged glutamic acid stabilizes FimH in the LAS conformation and replacement of Val-35 with glutamic acid traps FimH in the HAS conformation. The antibody is unable to trap the conformations if Leu-34 and Val-35 are replaced with a less bulky alanine. We propose that these residues act as molecular toggle switches and that the bound antibody imposes a steric block to their reorientation in either direction, thereby restricting concerted repacking of side chains that must occur to enable the conformational transition. Residues homologous to the FimH toggle switches are highly conserved across a diverse family of fimbrial adhesins. Replacement of predicted switch residues reveals that another E. coli adhesin, galactose-specific FmlH, is allosteric and can shift from an inactive to an active state. Our study shows that allosteric transitions in bacterial adhesins depend on toggle switch residues and that an antibody that blocks the switch effectively disables adhesive protein function. Public Library of Science 2021-04-07 /pmc/articles/PMC8064603/ /pubmed/33826682 http://dx.doi.org/10.1371/journal.ppat.1009440 Text en © 2021 Kisiela et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Kisiela, Dagmara I.
Magala, Pearl
Interlandi, Gianluca
Carlucci, Laura A.
Ramos, Angelo
Tchesnokova, Veronika
Basanta, Benjamin
Yarov-Yarovoy, Vladimir
Avagyan, Hovhannes
Hovhannisyan, Anahit
Thomas, Wendy E.
Stenkamp, Ronald E.
Klevit, Rachel E.
Sokurenko, Evgeni V.
Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title_full Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title_fullStr Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title_full_unstemmed Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title_short Toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
title_sort toggle switch residues control allosteric transitions in bacterial adhesins by participating in a concerted repacking of the protein core
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064603/
https://www.ncbi.nlm.nih.gov/pubmed/33826682
http://dx.doi.org/10.1371/journal.ppat.1009440
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