Crystal Structures of a CTXφ pIII Domain Unbound and in Complex with a Vibrio cholerae TolA Domain Reveal Novel Interaction Interfaces

Ford, C.G.; Kolappan, S.; Phan, H.T.; Waldor, Matthew K.; Winther‐Larsen, Hanne C.; Craig, Lisa

doi:10.1074/jbc.m112.403386

Cited by 17 publications

(31 citation statements)

References 64 publications

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“…In V. cholerae, TCP retraction seems central to the phage infection process, as TCP production alone is not sufficient to allow CTX⌽ uptake (14). Although TCP parasitism facilitates the introduction of CTX⌽ into the host cell, subsequent phage binding to TolA Vc appears to be the limiting step of the infection process (5,6,15). Thus, Heilpern and Waldor (5) have shown that a chimeric fd phage displaying the pIII-N1 CTX domain fused to the pIII-N3 fd domain can successfully infect V. cholerae cells.…”

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confidence: 99%

Electrostatic interactions between the CTX phage minor coat protein and the bacterial host receptor TolA drive the pathogenic conversion of Vibrio cholerae

Houot

Navarro²,

Nouailler

et al. 2017

Journal of Biological Chemistry

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is a natural inhabitant of aquatic environments and converts to a pathogen upon infection by a filamentous phage, CTXΦ, that transmits the cholera toxin-encoding genes. This toxigenic conversion of has evident implication in both genome plasticity and epidemic risk, but the early stages of the infection have not been thoroughly studied. CTXΦ transit across the bacterial periplasm requires binding between the minor coat protein named pIII and a bacterial inner-membrane receptor, TolA, which is part of the conserved Tol-Pal molecular motor. To gain insight into the TolA-pIII complex, we developed a bacterial two-hybrid approach, named Oxi-BTH, suited for studying the interactions between disulfide bond-folded proteins in the bacterial cytoplasm of an reporter strain. We found that two of the four disulfide bonds of pIII are required for its interaction with TolA. By combining Oxi-BTH assays, NMR, and genetic studies, we also demonstrate that two intermolecular salt bridges between TolA and pIII provide the driving forces of the complex interaction. Moreover, we show that TolA residue Arg-325 involved in one of the two salt bridges is critical for proper functioning of the Tol-Pal system. Our results imply that to prevent host evasion, CTXΦ uses an infection strategy that targets a highly conserved protein of Gram-negative bacteria essential for the fitness of in its natural environment.

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confidence: 99%

Electrostatic interactions between the CTX phage minor coat protein and the bacterial host receptor TolA drive the pathogenic conversion of Vibrio cholerae

Houot

Navarro²,

Nouailler

et al. 2017

Journal of Biological Chemistry

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“…We proposed previously that TCP might be retractile despite lacking a retraction ATPase, based on their functions in TcpF secretion, autoagglutination and phage uptake [106]. We wondered if TcpB might be involved in this process in addition to its role in initiating pilus assembly.…”

Section: Resultsmentioning

confidence: 99%

The Vibrio cholerae Minor Pilin TcpB Initiates Assembly and Retraction of the Toxin-Coregulated Pilus

Harn

Altindal

et al. 2016

PLoS Pathog

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Type IV pilus (T4P) systems are complex molecular machines that polymerize major pilin proteins into thin filaments displayed on bacterial surfaces. Pilus functions require rapid extension and depolymerization of the pilus, powered by the assembly and retraction ATPases, respectively. A set of low abundance minor pilins influences pilus dynamics by unknown mechanisms. The Vibrio cholerae toxin-coregulated pilus (TCP) is among the simplest of the T4P systems, having a single minor pilin TcpB and lacking a retraction ATPase. Here we show that TcpB, like its homolog CofB, initiates pilus assembly. TcpB co-localizes with the pili but at extremely low levels, equivalent to one subunit per pilus. We used a micropillars assay to demonstrate that TCP are retractile despite the absence of a retraction ATPase, and that retraction relies on TcpB, as a V. cholerae tcpB Glu5Val mutant is fully piliated but does not induce micropillars movements. This mutant is impaired in TCP-mediated autoagglutination and TcpF secretion, consistent with retraction being required for these functions. We propose that TcpB initiates pilus retraction by incorporating into the growing pilus in a Glu5-dependent manner, which stalls assembly and triggers processive disassembly. These results provide a framework for understanding filament dynamics in more complex T4P systems and the closely related Type II secretion system.

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“…Direct interaction between the TolAIII domain and the colicin A, E1, N, and K T-domain has been shown by numerous in vivo and in vitro experiments (82)(83)(84)(85). Similarly, the pIII protein at the tip of the phage particle is responsible for TolA binding (19,22,86,87). The phage pIII-N1 and pIII-N2 domains have been reported to bind E. coli TolAIII and TolAII domains, respectively (88).…”

Section: The Tol System Serves As a Versatile Import Machinery For Pamentioning

confidence: 98%

“…The structure of pIII-N1 and pIII-N1-N2 has been solved for the Ff and CTX phages by crystallography and NMR studies (Fig. 1B) (16,(18)(19)(20)(21)(22) Binding to the Primary Receptor and Crossing of the OM.…”

Section: Organizationmentioning

confidence: 99%

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Similarities and Differences between Colicin and Filamentous Phage Uptake by Bacterial Cells

Duché

Houot

2019

EcoSal Plus

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Gram-negative bacteria have evolved a complex envelope to adapt and survive in a broad range of ecological niches. This physical barrier is the first line of defense against noxious compounds and viral particles called bacteriophages. Colicins are a family of bactericidal proteins produced by and toxic to Escherichia coli and closely related bacteria. Filamentous phages have a complex structure, composed of at least five capsid proteins assembled in a long thread-shaped particle that protect the viral DNA. Despite their difference in size and complexity, group A colicins and filamentous phages both parasitize multiprotein complexes of their sensitive host for entry. They first bind to a receptor located at the surface of the target bacteria before specifically recruiting components of the Tol system to cross the outer membrane and find their way through the periplasm. The Tol system is thought to use the proton-motive force of the inner membrane to maintain outer membrane integrity during the life cycle of the cell. This review will describe the sequential docking mechanisms of group A colicins and filamentous phages during their uptake by their bacterial host, with a specific focus on the translocation step, promoted by interactions with the Tol system.

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Crystal Structures of a CTXφ pIII Domain Unbound and in Complex with a Vibrio cholerae TolA Domain Reveal Novel Interaction Interfaces

Cited by 17 publications

References 64 publications

Electrostatic interactions between the CTX phage minor coat protein and the bacterial host receptor TolA drive the pathogenic conversion of Vibrio cholerae

Electrostatic interactions between the CTX phage minor coat protein and the bacterial host receptor TolA drive the pathogenic conversion of Vibrio cholerae

The Vibrio cholerae Minor Pilin TcpB Initiates Assembly and Retraction of the Toxin-Coregulated Pilus

Similarities and Differences between Colicin and Filamentous Phage Uptake by Bacterial Cells

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