The role of Pseudomonas aeruginosa c-di-GMP metabolism proteins in antibiotic resistance.

Abstract

Following the genomic era, a large number of genes coding for enzymes predicted to synthesize and degrade 3'-5'-cyclic diguanylic acid (c-di-GMP) was found in most bacterial genomes and this dinucleotide emerged as an important intracellular signal molecule controlling bacterial behavior. Diverse molecular mechanisms have been described as targets for c-di-GMP, but several questions remain to be addressed. An association between high levels of c-di-GMP and antibiotic resistance is largely assumed, since high c-di-GMP upregulates biofilm formation and the biofilm mode of growth leads to enhanced antibiotic resistance; however, a clear understanding of this correlation is missing. Pseudomonas aeruginosa is a versatile gamma-proteobacterium that behaves as an opportunistic pathogen to a broad range of hosts. The ability of P. aeruginosa to form biofilms contributes to its virulence and adaptation to different environments. The P. aeruginosa PA14 genome presents several genes encoding proteins involved in metabolism or binding to c-di-GMP, which may indicate a wide regulatory role of this nucleotide in this bacterium. Recently, we found that overexpression of c-di-GMP in P. aeruginosa leads to increased resistance to the antibiotic imipenem, even in planktonic cells. This work intends to expand the understanding of how c-di-GMP levels are linked to antibiotic susceptibility. The minimum inhibitory concentration of some currently used antibiotics will be determined for strains mutant in each of the 42 genes involved in c-di-GMP metabolism and candidate interaction partners to these proteins will also be searched in a two-hybrid library. The data obtained here will not only result in a greater understanding of the physiology of bacteria, but also identify potential targets for the development of new anti-infective drugs.