The Rcs signal transduction pathway is triggered by ECA structure alterations in Serratia marcescens

CASTELLI, M. E.; GARCÍA VÉSCOVI, E.

JOURNAL OF BACTERIOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2011 vol. 193 p. 63 - 74

0021-9193

The enterobacterial common antigen (ECA) is a highly conserved exopolysaccharide in Gram-negativebacteria whose role remains largely uncharacterized. In a previous work, we have demonstrated that disruptingthe integrity of the ECA biosynthetic pathway imposed severe deficiencies to the Serratia marcescens motile(swimming and swarming) capacity. In this work, we show that alterations in the ECA structure activate theRcs phosphorelay, which results in the repression of the flagellar biogenesis regulatory cascade. In addition,a detailed analysis of wec cluster mutant strains, which provoke the disruption of the ECA biosynthesis atdifferent levels of the pathway, suggests that the absence of the periplasmic ECA cyclic structure couldconstitute a potential signal detected by the RcsF-RcsCDB phosphorelay. We also identify SMA1167 as amember of the S. marcescens Rcs regulon and show that high osmolarity induces Rcs activity in this bacterium.These results provide a new perspective from which to understand the phylogenetic conservation of ECA amongenterobacteria and the basis for the virulence attenuation detected in wec mutant strains in other pathogenicbacteria.