The EAL-domain protein FcsR regulates flagella, chemotaxis and type III secretion system in Pseudomonas aeruginosa by a phosphodiesterase independent mechanism

JESSICA ROSSELLO; ANALÍA LIMA; MAGDALENA GIL; JORGE RODRIGUEZ DUARTE; AGUSTÍN CORREA; PAULO CARVALHO; ARLINET KIERBEL; ROSARIO DURÁN

Scientific Reports

Nature Publishing Group

Año: 2017

2045-2322

Pseudomonas aeruginosa is an opportunistic pathogen that represents one of the most common causes of hospital-acquired infections. The ability of P. aeruginosa to switch from motile to sessile lifestyles is central to its pathogenicity, and is regulated by the second messenger c-di-GMP. A general feature of c-di-GMP metabolism is the presence of a surprisingly large number of genes coding enzymes that synthesize and degrade c-di-GMP: diguanylate cyclases and phosphodiesterases respectively. However, the physiological relevance of this apparent redundancy is still not clear, stressing the relevance of investigating the molecular function of each of these enzymes. In this work, we focused on the EAL domain containing phosphodiesterase PA2133. According to previous reports, overexpression of this enzyme impairs biofilm production and cytotoxicity, two processes relevant for disease development. Here, we phenotypically characterized P. aeruginosa strain K (PAK) overexpressing PA2133 and showed that biofilm formation and motility are severely impaired. Using complementary quantitative proteomic approaches to analyse membrane and exoprotein fractions, we showed that proteins that participate in three processes are mainly affected, namely flagellar motility, type III secretion system and chemotaxis. While inhibition of biofilm formation can be ascribed to the phosphodiesterase activity of PA2133, other effects are also observed using an enzymatically inactive point mutant. In particular, downregulation of flagellar, chemotaxis and type III secretion system proteins does not rely in phosphodiesterase activity. Based on this unexpected effect of PA2133 we propose to rename this gene product FcsR, for Flagellar, chemotaxis and type III secretion Regulator.