Tat substrate screen for P. aeruginosa PA14 mutants with defects in pqs signaling uncovers a role for the cytochrome bc₁ Rieske sub-unit.

(A) Comparison of peak pqsA expression in each of 34 Tat substrate mutants (S3 Table) transformed with a CTX::pqsA’-lux fusion compared with the PA14 wild type (white bar) and the ΔtatABC mutant (black bar). The bars represent mutants where pqsA expression is higher (green bar) or lower (grey bar) or the same (grey bar) as the wild type. PA14 mutant 27 (pink bar) has the lowest pqsA expression and carries a deletion in PA14-57570 (petA), the Rieske subunit of cytochrome bc₁. (B) Production of PQS, HHQ and HQNO after 16 h growth by P. aeruginosa PA14, the ΔtatABC and ΔpetA mutants and the genetically complemented PA14 mutant (ΔpetA::(CTX::petA)). ***p < 0.001, **p < 0.01, and *p < 0.05; n.s. not significant.