@article{Velázquez2026,

title = {Structural insights into the antibacterial function of the Pseudomonas putida effector Tke5},

author = {Carmen Velázquez and Maialen Zabala-Zearreta and Carmen Paredes and Cristina Civantos and Jon Altuna-Alvarez and Patricia Bernal and David Albesa-Jové},

doi = {10.1038/s44318-025-00689-6},

issn = {1460-2075},

year  = {2026},

date = {2026-01-12},

journal = {EMBO J},

publisher = {Springer Science and Business Media LLC},

abstract = {Abstract

                  

                    Pseudomonas putida

                    is a plant-beneficial rhizobacterium that encodes multiple type-VI secretion systems (T6SS) to outcompete phytopathogens in the rhizosphere. Among its antibacterial effectors, Tke5 (a member of the BTH_I2691 protein family) is a potent pore-forming toxin that disrupts ion homeostasis without causing considerable membrane damage. Tke5 harbours an N-terminal MIX domain, which is required for T6SS-dependent secretion in other systems. Many MIX domain-containing effectors require T6SS adaptor proteins (Tap) for secretion, but their molecular mechanisms of adaptor-effector binding remain elusive. Here, we report the 2.8 Å cryo-EM structure of the Tap3-Tke5 complex of

                    P. putida

                    strain KT2440, providing structural and functional insights into how effector Tke5 is recruited by its cognate adaptor protein Tap3. Functional dissection shows that the α-helical region of Tke5 is sufficient to kill intoxicated bacteria, while its β-rich region likely contributes to target membrane specificity. These findings delineate a mechanism of BTH_I2691 proteins for Tap recruitment and toxin activity, contributing to our understanding of a widespread yet understudied toxin family.

                  },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Martín-González2024,

title = {Selective cargo and membrane recognition by SNX17 regulates its interaction with Retriever},

author = {Aurora Martín-González and Iván Méndez-Guzmán and Maialen Zabala-Zearreta and Andrea Quintanilla and Arturo García-López and Eva Martínez-Lombardía and David Albesa-Jové and Juan Carlos Acosta and María Lucas},

doi = {10.1038/s44319-024-00340-1},

issn = {1469-3178},

year  = {2025},

date = {2025-01-27},

journal = {EMBO Rep},

volume = {26},

number = {2},

pages = {470--493},

publisher = {Springer Science and Business Media LLC},

abstract = {Abstract

                  The Retriever complex recycles a wide range of transmembrane proteins from endosomes to the plasma membrane. The cargo adapter protein SNX17 has been implicated in recruiting the Retriever complex to endosomal membranes, yet the details of this interaction have remained elusive. Through biophysical and structural model-guided mutagenesis studies with recombinant proteins and liposomes, we have gained a deeper understanding of this process. Here, we demonstrate a direct interaction between SNX17 and Retriever, specifically between the C-terminal region of SNX17 and the interface of the Retriever subunits VPS35L and VPS26C. This interaction is enhanced upon the binding of SNX17 to its cargo in solution, due to the disruption of an intramolecular autoinhibitory interaction between the C-terminal region of SNX17 and the cargo binding pocket. In addition, SNX17 binding to membranes containing phosphatidylinositol-3-phosphate also promotes Retriever recruitment in a cargo-independent manner. Therefore, this work provides evidence of the dual activation mechanisms by which SNX17 modulates Retriever recruitment to the proximity of cargo and membranes, offering significant insights into the regulatory mechanisms of protein recycling at endosomes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Rojas-Palomino2025b,

title = {Electrophysiological dissection of the ion channel activity of the Pseudomonas aeruginosa ionophore protein toxin Tse5},

author = {Jessica Rojas-Palomino and Jon Altuna-Alvarez and Amaia González-Magaña and María Queralt-Martín and David Albesa-Jové and Antonio Alcaraz},

doi = {10.1016/j.chemphyslip.2025.105472},

issn = {0009-3084},

year  = {2025},

date = {2025-03-00},

journal = {Chemistry and Physics of Lipids},

volume = {267},

publisher = {Elsevier BV},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Fridman2025,

title = {A new class of type VI secretion system effectors can carry two toxic domains and are recognized through the WHIX motif for export},

author = {Chaya Mushka Fridman and Kinga Keppel and Vladislav Rudenko and Jon Altuna-Alvarez and David Albesa-Jové and Eran Bosis and Dor Salomon},

editor = {Sebastian E. Winter},

doi = {10.1371/journal.pbio.3003053},

issn = {1545-7885},

year  = {2025},

date = {2025-03-17},

journal = {PLoS Biol},

volume = {23},

number = {3},

publisher = {Public Library of Science (PLoS)},

abstract = {Gram-negative bacteria employ the type VI secretion system (T6SS) to deliver toxic effectors into neighboring cells and outcompete rivals. Although many effectors have been identified, their secretion mechanism often remains unknown. Here, we describe WHIX, a domain sufficient to mediate the secretion of effectors via the T6SS. Remarkably, we find WHIX in T6SS effectors that contain a single toxic domain, as well as in effectors that contain two distinct toxic domains fused to either side of WHIX. We demonstrate that the latter, which we name double-blade effectors, require two cognate immunity proteins to antagonize their toxicity. Furthermore, we show that WHIX can be used as a chassis for T6SS-mediated secretion of multiple domains. Our findings reveal a new class of polymorphic T6SS cargo effectors with a unique secretion domain that can deploy two toxic domains in one shot, possibly reducing recipients’ ability to defend themselves.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Rojas-Palomino2025,

title = {The Pseudomonas aeruginosa Tse4 toxin assembles ion-selective and voltage-sensitive ion channels to couple membrane depolarisation with K+ efflux},

author = {Jessica Rojas-Palomino and Carmen Velázquez and Jon Altuna-Alvarez and Amaia González-Magaña and Maialen Zabala-Zearreta and Matthias Müller and María Queralt-Martín and Antonio Alcaraz and David Albesa-Jové},

editor = {Eric Cascales},

doi = {10.1371/journal.ppat.1012981},

issn = {1553-7374},

year  = {2025},

date = {2025-06-04},

journal = {PLoS Pathog},

volume = {21},

number = {6},

publisher = {Public Library of Science (PLoS)},

abstract = {

                    Pseudomonas aeruginosa

                    employs the Type VI secretion system (T6SS) to outcompete other bacteria in its environment. Among the effectors secreted by the T6SS of

                    P. aeruginosa

                    PAO1, Tse4 is known for its potent antibacterial activity. This study elucidates the molecular function of Tse4, which promotes cell depolarization in competing bacteria. Our results show that Tse4 spontaneously incorporates into lipid monolayers and forms multi-ionic channels in planar bilayers, with either ohmic conduction or diode-like rectifying currents and a preference for cations over anions. These observations allow us to propose a model of action whereby Tse4 channels couple cell depolarization with K

                    +

                    efflux. These insights into Tse4’s pore-forming activity enhance our understanding of bacterial competition and exemplify a finely tuned antibacterial strategy, coupling its ability to cause membrane depolarization with potassium efflux that synergises with other T6SS effectors. These results highlight the sophistication of

                    Pseudomonas aeruginosa

                    ’s competitive arsenal.

                  },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{González-Magaña2023,

title = {Structural and functional insights into the delivery of a bacterial Rhs pore-forming toxin to the membrane},

author = {Amaia González-Magaña and Igor Tascón and Jon Altuna-Alvarez and María Queralt-Martín and Jake Colautti and Carmen Velázquez and Maialen Zabala and Jessica Rojas-Palomino and Marité Cárdenas and Antonio Alcaraz and John C. Whitney and Iban Ubarretxena-Belandia and David Albesa-Jové},

doi = {10.1038/s41467-023-43585-5},

issn = {2041-1723},

year  = {2023},

date = {2023-12-00},

journal = {Nat Commun},

volume = {14},

number = {1},

publisher = {Springer Science and Business Media LLC},

abstract = {AbstractBacterial competition is a significant driver of toxin polymorphism, which allows continual compensatory evolution between toxins and the resistance developed to overcome their activity. Bacterial Rearrangement hot spot (Rhs) proteins represent a widespread example of toxin polymorphism. Here, we present the 2.45 Å cryo-electron microscopy structure of Tse5, an Rhs protein central to Pseudomonas aeruginosa type VI secretion system-mediated bacterial competition. This structural insight, coupled with an extensive array of biophysical and genetic investigations, unravels the multifaceted functional mechanisms of Tse5. The data suggest that interfacial Tse5-membrane binding delivers its encapsulated pore-forming toxin fragment to the target bacterial membrane, where it assembles pores that cause cell depolarisation and, ultimately, bacterial death.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{González-Magaña2022,

title = {The P. aeruginosa effector Tse5 forms membrane pores disrupting the membrane potential of intoxicated bacteria},

author = {Amaia González-Magaña and Jon Altuna and María Queralt-Martín and Eneko Largo and Carmen Velázquez and Itxaso Montánchez and Patricia Bernal and Antonio Alcaraz and David Albesa-Jové},

doi = {10.1038/s42003-022-04140-y},

issn = {2399-3642},

year  = {2022},

date = {2022-12-00},

journal = {Commun Biol},

volume = {5},

number = {1},

publisher = {Springer Science and Business Media LLC},

abstract = {Abstract

                  

                    The type VI secretion system (T6SS) of

                    Pseudomonas aeruginosa

                    injects effector proteins into neighbouring competitors and host cells, providing a fitness advantage that allows this opportunistic nosocomial pathogen to persist and prevail during the onset of infections. However, despite the high clinical relevance of

                    P. aeruginosa

                    , the identity and mode of action of most

                    P. aeruginosa

                    T6SS-dependent effectors remain to be discovered. Here, we report the molecular mechanism of Tse5-CT, the toxic auto-proteolytic product of the

                    P. aeruginosa

                    T6SS exported effector Tse5. Our results demonstrate that Tse5-CT is a pore-forming toxin that can transport ions across the membrane, causing membrane depolarisation and bacterial death. The membrane potential regulates a wide range of essential cellular functions; therefore, membrane depolarisation is an efficient strategy to compete with other microorganisms in polymicrobial environments.

                  },

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Nolan2021,

title = {Identification of Tse8 as a Type VI secretion system toxin from Pseudomonas aeruginosa that targets the bacterial transamidosome to inhibit protein synthesis in prey cells},

author = {Laura M. Nolan and Amy K. Cain and Thomas Clamens and R. Christopher D. Furniss and Eleni Manoli and Maria A. Sainz-Polo and Gordon Dougan and David Albesa-Jové and Julian Parkhill and Despoina A. I. Mavridou and Alain Filloux},

doi = {10.1038/s41564-021-00950-8},

issn = {2058-5276},

year  = {2021},

date = {2021-09-00},

journal = {Nat Microbiol},

volume = {6},

number = {9},

pages = {1199--1210},

publisher = {Springer Science and Business Media LLC},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{González-Magaña2020,

title = {Structural insights into Pseudomonas aeruginosa Type six secretion system exported effector 8},

author = {Amaia González-Magaña and M. Ángela Sainz-Polo and Gabriela Pretre and Retina Çapuni and María Lucas and Jon Altuna and Itxaso Montánchez and Paola Fucini and David Albesa-Jové},

doi = {10.1016/j.jsb.2020.107651},

issn = {1047-8477},

year  = {2020},

date = {2020-12-00},

journal = {Journal of Structural Biology},

volume = {212},

number = {3},

publisher = {Elsevier BV},

keywords = {},

pubstate = {published},

tppubtype = {article}

}