Distinct TssA proteins converge in coordinating tail biogenesis of the type VI secretion systems

Ali, Jemal; Lai, Erh‐Min

doi:10.1002/bies.202200219

Cited by 4 publications

(4 citation statements)

References 8 publications

(19 reference statements)

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“…In this study we have used P. aeruginosa as a model to investigate the diversity and specificity of T6SSs and their cognate TssA proteins. This is due to the great variability in the class of proteins encoded by tssA genes between different T6SSs: varying in size, domain organisation, symmetry, and structure 19 , 36 – 40 . One way this variation has been classified is grouping TssA proteins by size, i.e.…”

Section: Introductionmentioning

confidence: 99%

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

Fecht,

Paracuellos,

Subramoni

et al. 2024

Nat Commun

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The genome of Pseudomonas aeruginosa encodes three type VI secretion systems, each comprising a dozen distinct proteins, which deliver toxins upon T6SS sheath contraction. The least conserved T6SS component, TssA, has variations in size which influence domain organisation and structure. Here we show that the TssA Nt1 domain interacts directly with the sheath in a specific manner, while the C-terminus is essential for oligomerisation. We built chimeric TssA proteins by swapping C-termini and showed that these can be functional even when made of domains from different TssA sub-groups. Functional specificity requires the Nt1 domain, while the origin of the C-terminal domain is more permissive for T6SS function. We identify two regions in short TssA proteins, loop and hairpin, that contribute to sheath binding. We propose a docking mechanism of TssA proteins with the sheath, and a model for how sheath assembly is coordinated by TssA proteins from this position.

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Section: Introductionmentioning

confidence: 99%

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

Fecht,

Paracuellos,

Subramoni

et al. 2024

Nat Commun

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“…The MC interacts with the BP (Durand et al , 2015 ; Cherrak et al , 2018 ), which serves as a docking site of VgrG–PAAR–effector complex to initiate the polymerization of the tail (Zoued et al , 2016 ). The tail is composed of the Hcp inner tube and TssBC outer sheath, whose biogenesis is regulated by TssA cap protein, and when triggered, the sheath contracts and ejects out the effector decorated puncturing device into extracellular milieu or target cells (Basler et al , 2012 ; Vettiger & Basler, 2016 ; Ali & Lai, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

A glycine zipper motif is required for the translocation of a T6SS toxic effector into target cells

Ali

Sung

et al. 2023

EMBO Reports

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Type VI secretion systems (T6SSs) can deliver diverse toxic effectors into eukaryotic and bacterial cells. Although much is known about the regulation and assembly of T6SS, the translocation mechanism of effectors into the periplasm and/or cytoplasm of target cells remains elusive. Here, we use the Agrobacterium tumefaciens DNase effector Tde1 to unravel the mechanism of translocation from attacker to prey. We demonstrate that Tde1 binds to its adaptor Tap1 through the N‐terminus, which harbors continuous copies of GxxxG motifs resembling the glycine zipper structure found in proteins involved in the membrane channel formation. Amino acid substitutions on G39xxxG43 motif do not affect Tde1–Tap1 interaction and secretion but abolish its membrane permeability and translocation of its fluorescent fusion protein into prey cells. The data suggest that G39xxxG43 governs the delivery of Tde1 into target cells by permeabilizing the cytoplasmic membrane. Considering the widespread presence of GxxxG motifs in bacterial effectors and pore‐forming toxins, we propose that glycine zipper‐mediated permeabilization is a conserved mechanism used by bacterial effectors for translocation across target cell membranes.

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“…The TssB and TssC subunits are responsible for assembly of the contractile sheath, which is formed by hexamers of Hcp ( 9 – 11 ). Another core component of T6SS is TssA, an essential cap protein involved in coordinating tail polymerization ( 12 ). The tip of the spike is formed by a trimer of VgrG, a valine-glycine repeat protein, and PAAR, a proline-alanine-alanine-arginine repeat protein that facilitates delivery of specific effectors ( 13 – 15 ).…”

Section: Introductionmentioning

confidence: 99%

Sporulation Activated via σ ^W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector

et al. 2023

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The study of bacterial interactions is helping to define species-specific strategies used to modulate the competition dynamics underlying the development of community compositions. In this study, we deciphered the role of Pseudomonas T6SS when competing with Bacillus and the mechanism by which a T6SS-toxin modifies Bacillus physiology.

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Distinct TssA proteins converge in coordinating tail biogenesis of the type VI secretion systems

Cited by 4 publications

References 8 publications

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

A glycine zipper motif is required for the translocation of a T6SS toxic effector into target cells

Sporulation Activated via σ ^W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector

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Distinct TssA proteins converge in coordinating tail biogenesis of the type VI secretion systems

Cited by 4 publications

References 8 publications

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

Functionality of chimeric TssA proteins in the type VI secretion system reveals sheath docking specificity within their N-terminal domains

A glycine zipper motif is required for the translocation of a T6SS toxic effector into target cells

Sporulation Activated via σ W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector

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Product

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Sporulation Activated via σ ^W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector