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Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide
Lipopolysaccharide (LPS) is an essential component of the outer membrane (OM) of many Gram-negative bacteria, providing a barrier against the entry of toxic molecules. In Escherichia coli, LPS is exported to the cell surface by seven essential proteins (LptA-G) that form a transenvelope complex. At...
Autores principales: | , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Society for Microbiology
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9972910/ https://www.ncbi.nlm.nih.gov/pubmed/36541759 http://dx.doi.org/10.1128/mbio.02202-22 |
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author | Falchi, Federica A. Taylor, Rebecca J. Rowe, Sebastian J. Moura, Elisabete C. C. M. Baeta, Tiago Laguri, Cedric Simorre, Jean-Pierre Kahne, Daniel E. Polissi, Alessandra Sperandeo, Paola |
author_facet | Falchi, Federica A. Taylor, Rebecca J. Rowe, Sebastian J. Moura, Elisabete C. C. M. Baeta, Tiago Laguri, Cedric Simorre, Jean-Pierre Kahne, Daniel E. Polissi, Alessandra Sperandeo, Paola |
author_sort | Falchi, Federica A. |
collection | PubMed |
description | Lipopolysaccharide (LPS) is an essential component of the outer membrane (OM) of many Gram-negative bacteria, providing a barrier against the entry of toxic molecules. In Escherichia coli, LPS is exported to the cell surface by seven essential proteins (LptA-G) that form a transenvelope complex. At the inner membrane, the ATP-binding cassette (ABC) transporter LptB(2)FG associates with LptC to power LPS extraction from the membrane and transfer to the periplasmic LptA protein, which is in complex with the OM translocon LptDE. LptC interacts both with LptB(2)FG and LptADE to mediate the formation of the transenvelope bridge and regulates the ATPase activity of LptB(2)FG. A genetic screen has previously identified suppressor mutants at a residue (R212) of LptF that are viable in the absence of LptC. Here, we present in vivo evidence that the LptF R212G mutant assembles a six-protein transenvelope complex in which LptA mediates interactions with LptF and LptD in the absence of LptC. Furthermore, we present in vitro evidence that the mutant LptB(2)FG complexes restore the regulation of ATP hydrolysis as it occurs in the LptB(2)FGC complex to achieve wild-type efficient coupling of ATP hydrolysis and LPS movement. We also show the suppressor mutations restore the wild-type levels of LPS transport both in vivo and in vitro, but remarkably, without restoring the affinity of the inner membrane complex for LptA. Based on the sensitivity of lptF suppressor mutants to selected stress conditions relative to wild-type cells, we show that there are additional regulatory functions of LptF and LptC that had not been identified. |
format | Online Article Text |
id | pubmed-9972910 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Society for Microbiology |
record_format | MEDLINE/PubMed |
spelling | pubmed-99729102023-03-01 Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide Falchi, Federica A. Taylor, Rebecca J. Rowe, Sebastian J. Moura, Elisabete C. C. M. Baeta, Tiago Laguri, Cedric Simorre, Jean-Pierre Kahne, Daniel E. Polissi, Alessandra Sperandeo, Paola mBio Research Article Lipopolysaccharide (LPS) is an essential component of the outer membrane (OM) of many Gram-negative bacteria, providing a barrier against the entry of toxic molecules. In Escherichia coli, LPS is exported to the cell surface by seven essential proteins (LptA-G) that form a transenvelope complex. At the inner membrane, the ATP-binding cassette (ABC) transporter LptB(2)FG associates with LptC to power LPS extraction from the membrane and transfer to the periplasmic LptA protein, which is in complex with the OM translocon LptDE. LptC interacts both with LptB(2)FG and LptADE to mediate the formation of the transenvelope bridge and regulates the ATPase activity of LptB(2)FG. A genetic screen has previously identified suppressor mutants at a residue (R212) of LptF that are viable in the absence of LptC. Here, we present in vivo evidence that the LptF R212G mutant assembles a six-protein transenvelope complex in which LptA mediates interactions with LptF and LptD in the absence of LptC. Furthermore, we present in vitro evidence that the mutant LptB(2)FG complexes restore the regulation of ATP hydrolysis as it occurs in the LptB(2)FGC complex to achieve wild-type efficient coupling of ATP hydrolysis and LPS movement. We also show the suppressor mutations restore the wild-type levels of LPS transport both in vivo and in vitro, but remarkably, without restoring the affinity of the inner membrane complex for LptA. Based on the sensitivity of lptF suppressor mutants to selected stress conditions relative to wild-type cells, we show that there are additional regulatory functions of LptF and LptC that had not been identified. American Society for Microbiology 2022-12-21 /pmc/articles/PMC9972910/ /pubmed/36541759 http://dx.doi.org/10.1128/mbio.02202-22 Text en Copyright © 2023 Falchi et al. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/) . |
spellingShingle | Research Article Falchi, Federica A. Taylor, Rebecca J. Rowe, Sebastian J. Moura, Elisabete C. C. M. Baeta, Tiago Laguri, Cedric Simorre, Jean-Pierre Kahne, Daniel E. Polissi, Alessandra Sperandeo, Paola Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title | Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title_full | Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title_fullStr | Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title_full_unstemmed | Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title_short | Suppressor Mutations in LptF Bypass Essentiality of LptC by Forming a Six-Protein Transenvelope Bridge That Efficiently Transports Lipopolysaccharide |
title_sort | suppressor mutations in lptf bypass essentiality of lptc by forming a six-protein transenvelope bridge that efficiently transports lipopolysaccharide |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9972910/ https://www.ncbi.nlm.nih.gov/pubmed/36541759 http://dx.doi.org/10.1128/mbio.02202-22 |
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