Membrane Tethering of Honeybee Antimicrobial Peptides in Drosophila Enhances Pathogen Defense at the Cost of Stress-Induced Host Vulnerability

Antimicrobial peptides (AMPs) represent a promising alternative to conventional antibiotics in combating multidrug-resistant pathogens, yet their clinical translation is hindered by proteolytic instability, cytotoxicity, and poor bioavailability. Herein, it is demonstrated that glycosylphosphatidylinositol-mediated membrane tethering of honeybee defensin1 (Def1) in Drosophila melanogaster enhances its antimicrobial efficacy by 100-fold compared to secreted or untethered forms, while preserving physiological and behavioral integrity under baseline conditions. Using a genetically engineered Drosophila model, three Def1 variants are expressed: native (Def1), secreted (s-Def1), and membrane-tethered (t-Def1). Flies expressing t-Def1 exhibit superior bacterial clearance of Pseudomonas aeruginosa and show improved survival postinfection, with no adverse effects on locomotion, courtship, or sleep architecture. However, under stress paradigms—including sleep deprivation and dextran sulfate sodium (DSS)-induced gut injury—t-Def1 exacerbates intestinal barrier dysfunction, as evidenced by elevated Smurf phenotype incidence, highlighting a trade-off between antimicrobial potency and epithelial vulnerability. This work establishes Drosophila as a powerful platform for dissecting AMP mechanisms and engineering spatially targeted therapies, offering translational insights for pollinator health and human infectious disease management. These results advocate for iterative refinement of membrane-anchoring strategies to balance therapeutic efficacy with host safety, advancing the development of next-generation AMPs with minimized off-target effects. Graphical Confocal images showing bacterial proliferation in the Drosophila gut reveal antimicrobial activity of t-Def1(tethered defensin1) against Pseudomonas aeruginosa.