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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...
Autores principales: | , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2021
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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. |
format | Online Article Text |
id | pubmed-8064603 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
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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