9R8G

Pseudomonas putida Pore-Forming Toxin Tke5 in complex with its cognate Type VI adaptor protein Tap3

Summary for 9R8G

• Entry DOI: 10.2210/pdb9r8g/pdb
• EMDB information: 53820
• Descriptor: Toxin VasX N-terminal region domain-containing protein, DUF4123 domain-containing protein (2 entities in total)
• Functional Keywords: pseudomonas putida t6ss effector, pore-forming toxin, mix family domain, adaptor protein, toxin
• Biological source: Pseudomonas putida KT2440; More
• Total number of polymer chains: 2
• Total formula weight: 145613.93

Authors

Velazquez, C.,Zabala-Zearreta, M.,Altuna-Alvarez, J.,Albesa-Jove, D. (deposition date: 2025-05-16, release date: 2026-01-14, Last modification date: 2026-02-25)

Primary citation

Velazquez, C.,Zabala-Zearreta, M.,Paredes, C.,Civantos, C.,Altuna-Alvarez, J.,Bernal, P.,Albesa-Jove, D.
Structural insights into the antibacterial function of the Pseudomonas putida effector Tke5.
Embo J., 45:1229-1244, 2026

PubMed 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.

PubMed: 41526723
DOI: 10.1038/s44318-025-00689-6

Experimental method

ELECTRON MICROSCOPY (2.77 Å)