THE MOLECULAR MECHANISM OF IQS DOWNSTREAM SIGNALLING IN PSEUDOMONAS AERUGINOSA

Abstract

In P. aeruginosa Quorum Sensing, the las regulates the pqs and rhl systems. However, frequently occurring non-synonymous mutations in the las system of clinical isolates and las-independent regulation of the pqs and rhl systems under phosphate limitation has been observed. IQS takes over the regulation of pqs and rhl systems in a las-independent manner under phosphate limited conditions. To understand the mechanism of IQS signaling, we identified SadC, which encodes a c-di-GMP synthase by a genome-wide transposon mutagenesis assay as an indispensable factor for IQS control over the downstream pqs and rhl systems and virulence factors under phosphate limitation. By employing the bacterial two-hybrid assay, PvdQ was identified as an interacting partner for SadC and PhoB. PvdQ is positively regulated by PhoB under phosphate limited condition and regulates IQS downstream signaling. We also show that PvdQ enables the switch from las to IQS dominant signaling under phospho-depleted conditions.