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Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system

Many bacterial pathogens and symbionts use type III secretion machines to interact with their hosts by injecting bacterial effector proteins into host target cells. A central component of this complex machine is the cytoplasmic sorting platform, which orchestrates the engagement and preparation of t...

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Autores principales: Lara-Tejero, Maria, Qin, Zhuan, Hu, Bo, Butan, Carmen, Liu, Jun, Galán, Jorge E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6358110/
https://www.ncbi.nlm.nih.gov/pubmed/30668610
http://dx.doi.org/10.1371/journal.ppat.1007565
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author Lara-Tejero, Maria
Qin, Zhuan
Hu, Bo
Butan, Carmen
Liu, Jun
Galán, Jorge E.
author_facet Lara-Tejero, Maria
Qin, Zhuan
Hu, Bo
Butan, Carmen
Liu, Jun
Galán, Jorge E.
author_sort Lara-Tejero, Maria
collection PubMed
description Many bacterial pathogens and symbionts use type III secretion machines to interact with their hosts by injecting bacterial effector proteins into host target cells. A central component of this complex machine is the cytoplasmic sorting platform, which orchestrates the engagement and preparation of type III secreted proteins for their delivery to the needle complex, the substructure of the type III secretion system that mediates their passage through the bacterial envelope. The sorting platform is thought to be a dynamic structure whose components alternate between assembled and disassembled states. However, how this dynamic behavior is controlled is not understood. In S. Typhimurium a core component of the sorting platform is SpaO, which is synthesized in two tandemly translated products, a full length (SpaO(L)) and a short form (SpaO(S)) composed of the C-terminal 101 amino acids. Here we show that in the absence of SpaO(S) the assembly of the needle substructure of the needle complex, which requires a functional sorting platform, can still occur although with reduced efficiency. Consistent with this observation, in the absence of SpaO(S) secretion of effectors proteins, which requires a fully assembled injectisome, is only slightly compromised. In the absence of SpaO(S) we detect a significant number of fully assembled needle complexes that are not associated with fully assembled sorting platforms. We also find that although binding of SpaO(L) to SpaO(S) can be detected in the absence of other components of the sorting platform, this interaction is not detected in the context of a fully assembled sorting platform suggesting that SpaO(S) may not be a core structural component of the sorting platform. Consistent with this observation we find that SpaO(S) and OrgB, a component of the sorting platform, share the same binding surface on SpaO(L). We conclude that SpaO(S) regulates the assembly of the sorting platform during type III secretion.
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spelling pubmed-63581102019-02-22 Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system Lara-Tejero, Maria Qin, Zhuan Hu, Bo Butan, Carmen Liu, Jun Galán, Jorge E. PLoS Pathog Research Article Many bacterial pathogens and symbionts use type III secretion machines to interact with their hosts by injecting bacterial effector proteins into host target cells. A central component of this complex machine is the cytoplasmic sorting platform, which orchestrates the engagement and preparation of type III secreted proteins for their delivery to the needle complex, the substructure of the type III secretion system that mediates their passage through the bacterial envelope. The sorting platform is thought to be a dynamic structure whose components alternate between assembled and disassembled states. However, how this dynamic behavior is controlled is not understood. In S. Typhimurium a core component of the sorting platform is SpaO, which is synthesized in two tandemly translated products, a full length (SpaO(L)) and a short form (SpaO(S)) composed of the C-terminal 101 amino acids. Here we show that in the absence of SpaO(S) the assembly of the needle substructure of the needle complex, which requires a functional sorting platform, can still occur although with reduced efficiency. Consistent with this observation, in the absence of SpaO(S) secretion of effectors proteins, which requires a fully assembled injectisome, is only slightly compromised. In the absence of SpaO(S) we detect a significant number of fully assembled needle complexes that are not associated with fully assembled sorting platforms. We also find that although binding of SpaO(L) to SpaO(S) can be detected in the absence of other components of the sorting platform, this interaction is not detected in the context of a fully assembled sorting platform suggesting that SpaO(S) may not be a core structural component of the sorting platform. Consistent with this observation we find that SpaO(S) and OrgB, a component of the sorting platform, share the same binding surface on SpaO(L). We conclude that SpaO(S) regulates the assembly of the sorting platform during type III secretion. Public Library of Science 2019-01-22 /pmc/articles/PMC6358110/ /pubmed/30668610 http://dx.doi.org/10.1371/journal.ppat.1007565 Text en © 2019 Lara-Tejero et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://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
Lara-Tejero, Maria
Qin, Zhuan
Hu, Bo
Butan, Carmen
Liu, Jun
Galán, Jorge E.
Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title_full Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title_fullStr Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title_full_unstemmed Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title_short Role of SpaO in the assembly of the sorting platform of a Salmonella type III secretion system
title_sort role of spao in the assembly of the sorting platform of a salmonella type iii secretion system
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6358110/
https://www.ncbi.nlm.nih.gov/pubmed/30668610
http://dx.doi.org/10.1371/journal.ppat.1007565
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