RamA IS INVOLVED IN REGULATION OF THE LPS MODIFICATIONS AND RESISTANCE ANTIBIOTICS IN S. marcescens

ELEONORA GARCÍA VÉSCOVI; JAVIER FERNANDO MARISCOTTI

Parana

Congreso; LIV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular - SAIB

The lipopolysaccharide (LPS) lipid A is recognized by the innate system. The gram-negative bacteria modify the LPS to avoid host immune system and to resist killing by antimicrobial peptide. In many bacterial species, modifications in the LPS that confer resistance to antimicrobial peptides are regulated by the PhoP/PhoQ system. It was previously reported that, in Klebsiella pneumoniae, the RamA transcriptional regulator, functions as an alternate regulator of genes involved in lipid A biosynthesis. S. marcescens is an enteric bacterium that can function as an opportunistic pathogen within immunocompromised hosts. We found a ramA homolog gene in Serratia marcescens RM66262, and its promoter region a putative recognition site for the PhoP regulator. In this work, we analyzed the regulation of ramA and the genes lpxO1 and lpxO2 required for the modification of LPS in Serratia. The contribution of PhoP and RamA in the regulation of lpxO1 and lpxO2 was analyzed using gfp-containing reporter plasmids and electrophoretic mobility shift assay. Our results show that, in S. marcescens, PhoP is involved in the regulation of RamA expression and that both PhoP and RamA modulate the expression of the lpxO1 and lpxO2 genes. In addition, we showed that overproduction of RamA in S. marcescens reduces susceptibility to a tetracyclines, quinolones. The results suggest that RamA of S. marcescens participates in the regulation of LPS modifications and antibiotic resistance.