Biogenesis of outer membrane vesicles in Serratia marcescens is thermoregulated and can be induced by activation of the Rcs phosphorelay system

Kenneth J. McMahon, Maria E. Castelli, Eleonora García Vescovi, Mario F. Feldman

Research output: Contribution to journalArticlepeer-review

77 Scopus citations

Abstract

Outer membrane vesicles (OMVs) have been identified in a wide range of bacteria, yet little is known of their biogenesis. It has been proposed that OMVs can act as long-range toxin delivery vectors and as a novel stress response. We have found that the formation of OMVs in the Gram-negative opportunistic pathogen Serratia marcescens is thermoregulated, with a significant amount of OMVs produced at 22 or 30oC and negligible quantities formed at 37oC under laboratory conditions. Inactivation of the synthesis of the enterobacterial common antigen (ECA) resulted in a hypervesiculation phenotype, supporting the hypothesis that OMVs are produced in response to stress. We demonstrate that the phenotype can be reversed to wild-type (WT) levels upon the loss of the Rcs phosphorelay response regulator RcsB, but not RcsA, suggesting a role for the Rcs phosphorelay in the production of OMVs. MS fingerprinting of the OMVs provided evidence of cargo selection within wild-type cells, suggesting a possible role for Serratia OMVs in toxin delivery. In addition, OMV-associated cargo proved toxic upon injection into the haemocoel of Galleria mellonella larvae. These experiments demonstrate that OMVs are the result of a regulated process in Serratia and suggest that OMVs could play a role in virulence.

Original languageEnglish
Pages (from-to)3241-3249
Number of pages9
JournalJournal of bacteriology
Volume194
Issue number12
DOIs
StatePublished - Jun 2012

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