The phosphodiesterase RmcA contributes to the adaptation of Pseudomonas putida to L-arginine.

Amino acids are crucial in nitrogen cycling and to shape the metabolism of microorganisms. Among them, arginine is a versatile molecule able to sustain nitrogen, carbon and even ATP supply and to regulate multicellular behaviors such as biofilm formation. Arginine modulates the intracellular levels of 3'-5'cyclic diguanylic acid (c-di-GMP), a second messenger that controls biofilm formation, maintenance and dispersion. In Pseudomonas putida KT2440, a versatile microorganism with wide biotechnological applications, modulation of c-di-GMP levels by arginine requires the transcriptional regulator ArgR, but the connections between arginine metabolism and c-di-GMP are not fully characterized. It has been recently demonstrated that arginine can be perceived by the opportunistic human pathogen Pseudomonas aeruginosa through the transducer RmcA protein (Redox regulator of c-di-GMP), which can directly decrease c-di-GMP levels and possibly affect biofilm architecture. A RmcA homolog is present in P. putida, but its function and involvement in arginine perceiving or biofilm life cycle had not been studied. Here we present a preliminary characterization of the RmcA-dependent response to arginine in P. putida in modulating biofilm formation, c-di-GMP levels and energy metabolism. This work contributes to further understanding the molecular mechanisms linking biofilm homeostasis and environmental adaptation.