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Structural basis of cooperative neutralization of the PldB toxin by immunity proteins in Pseudomonas aeruginosa

Xiaoyun Yang1, Jiawen Yang1, Hong Wang1,2

  • 1Department of Pharmacology, SUSTech Homeostatic Medicine Institute, School of Medicine, Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, China.

Communications Biology
|July 14, 2026
PubMed

Insights

Multidrug-resistant Pseudomonas aeruginosa uses phospholipase D (PldB) to harm host cells. Three immunity proteins (PA5086, PA5087, PA5088) cooperatively neutralize PldB toxicity by blocking its active site.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Pseudomonas aeruginosa is a multidrug-resistant pathogen.
  • Type VI secretion systems (T6SS) deliver effector proteins into host cells.
  • Phospholipase D (PLD) effectors like PldB disrupt host cell membranes.

Purpose of the Study:

  • To elucidate the mechanism by which immunity proteins PA5086, PA5087, and PA5088 neutralize PldB toxicity.
  • To understand the structural basis of PldB-immunity protein interactions.

Main Methods:

  • Quantitative and qualitative analyses of protein interactions.
  • Cryogenic electron microscopy (Cryo-EM) of the PldB-PA5088 complex.
  • Enzyme activity assays and domain-specific truncation studies.

Main Results:

  • PA5086, PA5087, and PA5088 cooperatively inhibit PldB cytotoxicity.
  • PA5088 binds to the HKD2 domain of PldB via electrostatic interactions, obstructing the active site.
  • Distinct binding regions and copy numbers for each immunity protein were identified.

Conclusions:

  • The study provides mechanistic insights into PldB neutralization by cognate immunity proteins.
  • This understanding can inform the development of novel therapeutics targeting PldB in P. aeruginosa infections.

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