Bacterial alkaloids prevent amoebal predation.
Bacterial defense mechanisms evolved to protect against predation from nematodes, predatory bacteria or amoebae. We identified novel bacterial alkaloids (pyreudione A – D) that are necessary for protection of the producer, Pseudomonas fluorescens HKI0770, against amoebal predation. We describe the isolation, structure elucidation, total synthesis, and a proposed biosynthetic pathway for these structures. Generation of P. fluorescens gene deletion mutants, unable to produce pyreudiones, render the bacterium edible to a variety of soil-dwelling amoebae.