BacA: a possible regulator that contributes to the biofilm formation of Pseudomonas aeruginosa
Lisa Wallart, Mohamed Amine Ben Mlouka, Brahim Saffiedine, Laurent Coquet, Hung Lê, Julie Hardouin, Thierry Jouenne, Gilles Phan, Marie‐Christine Kiefer‐Meyer, Éric Girard, Isabelle Broutin, Pascal Cosette
Abstract
Previously, we pointed out in P. aeruginosa PAO1 biofilm cells the accumulation of a hypothetical protein named PA3731 and showed that the deletion of the corresponding gene impacted its biofilm formation capacity. PA3731 belongs to a cluster of 4 genes ( pa3732 to pa3729 ) that we named bac for “Biofilm Associated Cluster.” The present study focuses on the PA14_16140 protein, i.e., the PA3732 (BacA) homolog in the PA14 strain. The role of BacA in rhamnolipid secretion, biofilm formation and virulence, was confirmed by phenotypic experiments with a bacA mutant. Additional investigations allow to advance that the bac system involves in fact 6 genes organized in operon, i.e., bacA to bacF. At a molecular level, quantitative proteomic studies revealed an accumulation of the BAC cognate partners by the bacA sessile mutant, suggesting a negative control of BacA toward the bac operon. Finally, a first crystallographic structure of BacA was obtained revealing a structure homologous to chaperones or/and regulatory proteins.