A bacterial chaperone-usher pathway links interkingdom association to antimicrobial protection of a fungal partner

In Paraburkholderia edwinii, divergent archaic chaperone-usher (CUP) “fac” genes promote attachment and are required for sequestration and detoxification of phenazine-1-carboxylic acid (PCA) to enable full fungal protection.

• Why it matters: PCA shapes microbial community composition in the rhizosphere, but how a PCA-tolerant bacterium protects a PCA-susceptible fungus via interkingdom mechanisms is unclear.
• What they did: Using a ΔhrcA strain to drive constitutive protection, the study identified fac genes in a divergent archaic CUP operon and tested their roles in bacterial-fungal attachment and PCA handling, plus mapped regulation by FacR.
• The result: fac genes enhance bacterial-fungal attachment and are required for P. edwinii to sequester and detoxify PCA, supporting complete Aspergillus calidoustus protection from PCA stress, while not being needed for P. edwinii PCA tolerance.

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