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The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division

The FtsLB complex is a key regulator of bacterial cell division, existing in either an off state or an on state, which supports the activation of septal peptidoglycan synthesis. In Escherichia coli, residues known to be critical for this activation are located in a region near the C-terminal end of...

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Autores principales: Craven, Samuel J., Condon, Samson G.F., Díaz Vázquez, Gladys, Cui, Qiang, Senes, Alessandro
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8749076/
https://www.ncbi.nlm.nih.gov/pubmed/34871549
http://dx.doi.org/10.1016/j.jbc.2021.101460
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author Craven, Samuel J.
Condon, Samson G.F.
Díaz Vázquez, Gladys
Cui, Qiang
Senes, Alessandro
author_facet Craven, Samuel J.
Condon, Samson G.F.
Díaz Vázquez, Gladys
Cui, Qiang
Senes, Alessandro
author_sort Craven, Samuel J.
collection PubMed
description The FtsLB complex is a key regulator of bacterial cell division, existing in either an off state or an on state, which supports the activation of septal peptidoglycan synthesis. In Escherichia coli, residues known to be critical for this activation are located in a region near the C-terminal end of the periplasmic coiled-coil domain of FtsLB, raising questions about the precise role of this conserved domain in the activation mechanism. Here, we investigate an unusual cluster of polar amino acids found within the core of the FtsLB coiled coil. We hypothesized that these amino acids likely reduce the structural stability of the domain and thus may be important for governing conformational changes. We found that mutating these positions to hydrophobic residues increased the thermal stability of FtsLB but caused cell division defects, suggesting that the coiled-coil domain is a “detuned” structural element. In addition, we identified suppressor mutations within the polar cluster, indicating that the precise identity of the polar amino acids is important for fine-tuning the structural balance between the off and on states. We propose a revised structural model of the tetrameric FtsLB (named the “Y-model”) in which the periplasmic domain splits into a pair of coiled-coil branches. In this configuration, the hydrophilic terminal moieties of the polar amino acids remain more favorably exposed to water than in the original four-helix bundle model (“I-model”). We propose that a shift in this architecture, dependent on its marginal stability, is involved in activating the FtsLB complex and triggering septal cell wall reconstruction.
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spelling pubmed-87490762022-01-13 The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division Craven, Samuel J. Condon, Samson G.F. Díaz Vázquez, Gladys Cui, Qiang Senes, Alessandro J Biol Chem Research Article The FtsLB complex is a key regulator of bacterial cell division, existing in either an off state or an on state, which supports the activation of septal peptidoglycan synthesis. In Escherichia coli, residues known to be critical for this activation are located in a region near the C-terminal end of the periplasmic coiled-coil domain of FtsLB, raising questions about the precise role of this conserved domain in the activation mechanism. Here, we investigate an unusual cluster of polar amino acids found within the core of the FtsLB coiled coil. We hypothesized that these amino acids likely reduce the structural stability of the domain and thus may be important for governing conformational changes. We found that mutating these positions to hydrophobic residues increased the thermal stability of FtsLB but caused cell division defects, suggesting that the coiled-coil domain is a “detuned” structural element. In addition, we identified suppressor mutations within the polar cluster, indicating that the precise identity of the polar amino acids is important for fine-tuning the structural balance between the off and on states. We propose a revised structural model of the tetrameric FtsLB (named the “Y-model”) in which the periplasmic domain splits into a pair of coiled-coil branches. In this configuration, the hydrophilic terminal moieties of the polar amino acids remain more favorably exposed to water than in the original four-helix bundle model (“I-model”). We propose that a shift in this architecture, dependent on its marginal stability, is involved in activating the FtsLB complex and triggering septal cell wall reconstruction. American Society for Biochemistry and Molecular Biology 2021-12-04 /pmc/articles/PMC8749076/ /pubmed/34871549 http://dx.doi.org/10.1016/j.jbc.2021.101460 Text en © 2021 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Research Article
Craven, Samuel J.
Condon, Samson G.F.
Díaz Vázquez, Gladys
Cui, Qiang
Senes, Alessandro
The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title_full The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title_fullStr The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title_full_unstemmed The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title_short The coiled-coil domain of Escherichia coli FtsLB is a structurally detuned element critical for modulating its activation in bacterial cell division
title_sort coiled-coil domain of escherichia coli ftslb is a structurally detuned element critical for modulating its activation in bacterial cell division
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8749076/
https://www.ncbi.nlm.nih.gov/pubmed/34871549
http://dx.doi.org/10.1016/j.jbc.2021.101460
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