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A novel stabilization mechanism for the type VI secretion system sheath

The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the assembly of the T6SS sheath structure, the contraction of which propels a payload of effector proteins into neighbori...

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Autores principales: Bernal, Patricia, Furniss, R. Christopher D., Fecht, Selina, Leung, Rhoda C. Y., Spiga, Livia, Mavridou, Despoina A. I., Filloux, Alain
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896307/
https://www.ncbi.nlm.nih.gov/pubmed/33558227
http://dx.doi.org/10.1073/pnas.2008500118
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author Bernal, Patricia
Furniss, R. Christopher D.
Fecht, Selina
Leung, Rhoda C. Y.
Spiga, Livia
Mavridou, Despoina A. I.
Filloux, Alain
author_facet Bernal, Patricia
Furniss, R. Christopher D.
Fecht, Selina
Leung, Rhoda C. Y.
Spiga, Livia
Mavridou, Despoina A. I.
Filloux, Alain
author_sort Bernal, Patricia
collection PubMed
description The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the assembly of the T6SS sheath structure, the contraction of which propels a payload of effector proteins into neighboring cells. Despite their key function, TssA proteins exhibit unexpected diversity and exist in two major forms, a short form (TssA(S)) and a long form (TssA(L)). While TssA(L) proteins interact with a partner, called TagA, to anchor the distal end of the extended sheath, the mechanism for the stabilization of TssA(S)-containing T6SSs remains unknown. Here we discover a class of structural components that interact with short TssA proteins and contribute to T6SS assembly by stabilizing the polymerizing sheath from the baseplate. We demonstrate that the presence of these components is important for full sheath extension and optimal firing. Moreover, we show that the pairing of each form of TssA with a different class of sheath stabilization proteins results in T6SS apparatuses that either reside in the cell for some time or fire immediately after sheath extension. We propose that this diversity in firing dynamics could contribute to the specialization of the T6SS to suit bacterial lifestyles in diverse environmental niches.
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spelling pubmed-78963072021-02-24 A novel stabilization mechanism for the type VI secretion system sheath Bernal, Patricia Furniss, R. Christopher D. Fecht, Selina Leung, Rhoda C. Y. Spiga, Livia Mavridou, Despoina A. I. Filloux, Alain Proc Natl Acad Sci U S A Biological Sciences The type VI secretion system (T6SS) is a phage-derived contractile nanomachine primarily involved in interbacterial competition. Its pivotal component, TssA, is indispensable for the assembly of the T6SS sheath structure, the contraction of which propels a payload of effector proteins into neighboring cells. Despite their key function, TssA proteins exhibit unexpected diversity and exist in two major forms, a short form (TssA(S)) and a long form (TssA(L)). While TssA(L) proteins interact with a partner, called TagA, to anchor the distal end of the extended sheath, the mechanism for the stabilization of TssA(S)-containing T6SSs remains unknown. Here we discover a class of structural components that interact with short TssA proteins and contribute to T6SS assembly by stabilizing the polymerizing sheath from the baseplate. We demonstrate that the presence of these components is important for full sheath extension and optimal firing. Moreover, we show that the pairing of each form of TssA with a different class of sheath stabilization proteins results in T6SS apparatuses that either reside in the cell for some time or fire immediately after sheath extension. We propose that this diversity in firing dynamics could contribute to the specialization of the T6SS to suit bacterial lifestyles in diverse environmental niches. National Academy of Sciences 2021-02-16 2021-02-08 /pmc/articles/PMC7896307/ /pubmed/33558227 http://dx.doi.org/10.1073/pnas.2008500118 Text en Copyright © 2021 the Author(s). Published by PNAS. http://creativecommons.org/licenses/by/4.0/ https://creativecommons.org/licenses/by/4.0/This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Biological Sciences
Bernal, Patricia
Furniss, R. Christopher D.
Fecht, Selina
Leung, Rhoda C. Y.
Spiga, Livia
Mavridou, Despoina A. I.
Filloux, Alain
A novel stabilization mechanism for the type VI secretion system sheath
title A novel stabilization mechanism for the type VI secretion system sheath
title_full A novel stabilization mechanism for the type VI secretion system sheath
title_fullStr A novel stabilization mechanism for the type VI secretion system sheath
title_full_unstemmed A novel stabilization mechanism for the type VI secretion system sheath
title_short A novel stabilization mechanism for the type VI secretion system sheath
title_sort novel stabilization mechanism for the type vi secretion system sheath
topic Biological Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7896307/
https://www.ncbi.nlm.nih.gov/pubmed/33558227
http://dx.doi.org/10.1073/pnas.2008500118
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