The various and varying roles of specific chaperones in type III secretion systems

Parsot, Claude; Hamiaux, Cyril; Page, Anne‐Laure

doi:10.1016/s1369-5274(02)00002-4

Cited by 243 publications

(316 citation statements)

References 59 publications

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“…These chaperones are all less than 20 kDa (11-15 kDa), generally have an acidic pI, are cytosolic, and contain a C-terminal amphipathic helix required for partner binding. A range of documented functions for chaperones have been reported, including stabilizing the partner before secretion and acting as a secretion pilot during effector tranlocation (Parsot et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…Class I chaperones are the best characterized, and all bind a discrete domain within the N-terminus of their partner (Parsot et al, 2003). They dimerize and share remarkable structural similarity, despite the lack of significant sequence similarity.…”

Section: Classification Of the Ssea Chaperonementioning

confidence: 99%

“…TTS chaperones are often required for translocon pore protein stability, prior to export, and for export to the bacterial surface to occur (reviewed by Bennett & Hughes, 2000;Parsot et al, 2003). TTS chaperones are energy-independent and transiently associate with one or several export targets.…”

Section: Introductionmentioning

confidence: 99%

“…Most TTS chaperones are small, have an acidic pI and contain an amphipathic C-terminal helix. Characterized chaperones are currently discriminated into three groups based on whether their partner is an effector (group I), a pair of translocon pore proteins (group II) or a flagellar component (group III) (Parsot et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…SseA is a chaperone for a putative translocon sheath protein and a single, putative translocon pore protein. This constitutes a unique set of binding partners when compared to the other classified chaperones (Parsot et al, 2003). Furthermore, a range of SseA physical features, such as its basic pI and partial membrane association, are also atypical of virulence chaperone proteins (Zurawski & Stein, 2003).…”

Section: Introductionmentioning

confidence: 99%

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The SPI2-encoded SseA chaperone has discrete domains required for SseB stabilization and export, and binds within the C-terminus of SseB and SseD

Zurawski

Stein

2004

Microbiology

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SseA, a key Salmonella virulence determinant, is a small, basic pI protein encoded within the Salmonella pathogenicity island 2 and serves as a type III secretion system chaperone for SseB and SseD. Both SseA partners are subunits of the surface-localized translocon module that delivers effectors into the host cell; SseB is predicted to compose the translocon sheath and SseD is a putative translocon pore subunit. In this study, SseA molecular interactions with its partners were characterized further. Yeast two-hybrid screens indicate that SseA binding requires a C-terminal domain within both partners. An additional central domain within SseD was found to influence binding. The SseA-binding region within SseB was found to encompass a predicted amphipathic helix of a type participating in coiled-coil interactions that are implicated in the assembly of translocon sheaths. Deletions that impinge upon this putative coiled-coiled domain prevent SseA binding, suggesting that SseA occupies a portion of the coiled-coil. SseA occupancy of this motif is envisioned to be sufficient to prevent premature SseB self-association inside bacteria. Domain mapping on the chaperone was also performed. A deletion of the SseA N-terminus, or site-directed mutations within this region, allowed stabilization of SseB, but its export was disrupted. Therefore, the N-terminus of SseA provides a function that is essential for SseB export, but dispensable for partner binding and stabilization.

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Section: Discussionmentioning

confidence: 99%

Section: Classification Of the Ssea Chaperonementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The SPI2-encoded SseA chaperone has discrete domains required for SseB stabilization and export, and binds within the C-terminus of SseB and SseD

Zurawski

Stein

2004

Microbiology

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The sorting platform in the type III secretion pathway: From assembly to function

Soto

Lara‐Tejero

2023

BioEssays

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The type III secretion system (T3SS) is a specialized nanomachine that enables bacteria to secrete proteins in a specific order and directly deliver a specific set of them, collectively known as effectors, into eukaryotic organisms. The core structure of the T3SS is a syringe‐like apparatus composed of multiple building blocks, including both membrane‐associated and soluble proteins. The cytosolic components organize together in a chamber‐like structure known as the sorting platform (SP), responsible for recruiting, sorting, and initiating the substrates destined to engage this secretion pathway. In this article, we provide an overview of recent findings on the SP's structure and function, with a particular focus on its assembly pathway. Furthermore, we discuss the molecular mechanisms behind the recruitment and hierarchical sorting of substrates by this cytosolic complex. Overall, the T3SS is a highly specialized and complex system that requires precise coordination to function properly. A deeper understanding of how the SP orchestrates T3S could enhance our comprehension of this complex nanomachine, which is central to the host‐pathogen interface, and could aid in the development of novel strategies to fight bacterial infections.

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Mapping of the chaperone AcrH binding regions of translocators AopB and AopD and characterization of oligomeric and metastable AcrH‐AopB‐AopD complexes in the type III secretion system of Aeromonas hydrophila

Tan

Sivaraman

et al. 2009

Protein Science

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In the type III secretion system (T3SS) of Aeromonas hydrophila, AcrH acts as a chaperone for translocators AopB and AopD. AcrH forms a stable 1:1 monomeric complex with AopD, whereas the 1:1 AcrH-AopB complex exists mainly as a metastable oligomeric form and only in minor amounts as a stable monomeric form. Limited protease digestion shows that these complexes contain highly exposed regions, thus allowing mapping of intact functional chaperone binding regions of AopB and AopD. AopD uses the transmembrane domain (DF1, residues 16-147) and the C-terminal amphipathic helical domain (DF2, residues 242-296) whereas AopB uses a discrete region containing the transmembrane domain and the putative N-terminal coiled coil domain (BF1, residues 33-264). Oligomerization of the AcrH-AopB complex is mainly through the C-terminal coiled coil domain of AopB, which is dispensable for chaperone binding. The three proteins, AcrH, AopB, and AopD, can be coexpressed to form an oligomeric and metastable complex. These three proteins are also oligomerized mainly through the C-terminal domain of AopB. Formation of such an oligomeric and metastable complex may be important for the proper formation of translocon of correct topology and stoichiometry on the host membrane.

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The various and varying roles of specific chaperones in type III secretion systems

Cited by 243 publications

References 59 publications

The SPI2-encoded SseA chaperone has discrete domains required for SseB stabilization and export, and binds within the C-terminus of SseB and SseD

The SPI2-encoded SseA chaperone has discrete domains required for SseB stabilization and export, and binds within the C-terminus of SseB and SseD

The sorting platform in the type III secretion pathway: From assembly to function

Mapping of the chaperone AcrH binding regions of translocators AopB and AopD and characterization of oligomeric and metastable AcrH‐AopB‐AopD complexes in the type III secretion system of Aeromonas hydrophila

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