Structural insights into the antibacterial function of the Pseudomonas putida effector Tke5
Year: 2026
Type: article
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.
Source: The EMBO Journal
Authors: Carmen Velázquez, Maialen Zabala-Zearreta, Carmen Paredes, Cristina Civantos, Jon Altuna-Alvarez, Patricia Bernal, David Albesa-Jové
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $7,990
Awards: G1175115578, G121809054, G1338257350, G143639328, G164292983, G1679087348, G1855990336, G2064873908, G210041235, G2262748287, G2309174360, G2390397592, G2585926585, G2601397997, G2660406951, G279363373, G3005324705, G300979063, G34346518, G3480869486, G3644880863, G3681454997, G4042783231, G410571670, G425668148, G430777504, G451917667, G4974793502, G5080475149, G5421974903, G586857820, G5967599077, G6206575485, G6636838885, G69051668, G7084143925, G7391727506, G7644056297, G8056732889, G846842501, G8667108890, G897484643, G929308097, G99296377
OpenAlex ID: W7122704263