Identification and Characterization of Outer Membrane Vesicle-Associated Proteins in Salmonella enterica Serovar Typhimurium

Abstract

dSalmonella enterica serovar Typhimurium is a primary cause of enteric diseases and has acquired a variety of virulence factors during its evolution into a pathogen. Secreted virulence factors interact with commensal flora and host cells and enable Salmonella to survive and thrive in hostile environments. Outer membrane vesicles (OMVs) released from many Gram-negative bacteria function as a mechanism for the secretion of complex mixtures, including virulence factors. We performed a proteomic analysis of OMVs that were isolated under standard laboratory and acidic minimal medium conditions and identified 14 OMVassociated proteins that were observed in the OMV fraction isolated only under the acidic minimal medium conditions, which reproduced the nutrient-deficient intracellular milieu. The inferred roles of these 14 proteins were diverse, including transporter, enzyme, and transcriptional regulator. The absence of these proteins influenced Salmonella survival inside murine macrophages. Eleven of these proteins were predicted to possess secretion signal sequences at their N termini, and three (HupA, GlnH, and PhoN) of the proteins were found to be translocated into the cytoplasm of host cells. The comparative proteomic profiling of OMVs performed in this study revealed different protein compositions in the OMVs isolated under the two different conditions, which indicates that the OMV cargo depends on the growth conditions and provides a deeper insight into how Salmonella utilizes OMVs to adapt to environmental changes.

SalmonellaCholeraesuis outer membrane vesicles: Proteomics and immunogenicity

“…Remarkably, a large number of cytoplasmic proteins (34.9%) were also identified in S. Choleraesuis OMVs. Bai and their colleagues also found this phenomenon in natural S. Typhimurium OMVs and explained that these cytoplasmic proteins might relocalized in the outer membrane or periplasm as cargo proteins, since these proteins are more apt to be entrapped in natural OMVs to fulfill biological function [30]. Overall, our study provides a detailed knowledge regarding S. Choleraesuis OMVs, which contributes to elucidating the pathogenic functions of OMVs from S. Choleraesuis.…”

“…Bai and their colleagues also found this phenomenon in natural S . Typhimurium OMVs and explained that these cytoplasmic proteins might relocalized in the outer membrane or periplasm as cargo proteins, since these proteins are more apt to be entrapped in natural OMVs to fulfill biological function . Overall, our study provides a detailed knowledge regarding S .…”

“…OMV‐mediated translocation associated with SPI effectors in the further research may reveal a better understanding of host‐pathogen interaction of S . Choleraesuis via OMV secretion .…”

“…In the study presented here, the major protein associated with SPI-1 T3SS, including SipC, SopB, SipA, and SipB, were identified ( Table 1), indicating that OMVs might incorporate T3SS. OMV-mediated translocation associated with SPI effectors in the further research may reveal a better understanding of host-pathogen interaction of S. Choleraesuis via OMV secretion [30].…”

Environmentally controlled bacterial vesicle-mediated export

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