Differences in Salmonella enterica serovar Typhimurium strain invasiveness are associated with heterogeneity in SPI-1 gene expression

Clark, Leann and Perrett, Charlotte A. and Malt, Layla and Harward, Caryn and Humphrey, Suzanne and Jepson, Katy A. and Martinez-Argudo, Isabel and Carney, Laura J. and La Ragione, Roberto M. and Humphrey, Tom J. and Jepson, Mark A. (2011) Differences in Salmonella enterica serovar Typhimurium strain invasiveness are associated with heterogeneity in SPI-1 gene expression. Microbiology, 157 (7). pp. 2072-2083. ISSN 1465-2080 (https://doi.org/10.1099/mic.0.048496-0)

[thumbnail of Clark-etal-Microbiology-2011-Differences-in-Salmonella-enterica-serovar-Typhimurium-strain-invasiveness]
Preview
 Text. Filename: Clark-etal-Microbiology-2011-Differences-in-Salmonella-enterica-serovar-Typhimurium-strain-invasiveness.pdf
Final Published Version
License: Creative Commons Attribution 3.0 logo
Download (566kB)| Preview

Abstract

Most studies on Salmonella enterica serovar Typhimurium infection focus on strains ATCC SL1344 or NTCC 12023 (ATCC 14028). We have compared the abilities of these strains to induce membrane ruffles and invade epithelial cells. S. Typhimurium strain 12023 is less invasive and induces smaller membrane ruffles on MDCK cells compared with SL1344. Since the SPI-1 effector SopE is present in SL1344 and absent from 12023, and SL1344 sopE mutants have reduced invasiveness, we investigated whether 12023 is less invasive due to the absence of SopE. However, comparison of SopE+ and SopE− S. Typhimurium strains, sopE deletion mutants and 12023 expressing a sopE plasmid revealed no consistent relationship between SopE status and relative invasiveness. Nevertheless, absence of SopE was closely correlated with reduced size of membrane ruffles. A PprgH–gfp reporter revealed that relatively few of the 12023 population (and that of the equivalent strain ATCC 14028) express SPI-1 compared to other S. Typhimurium strains. Expression of a PhilA–gfp reporter mirrored that of PprgH–gfp in 12023 and SL1344, implicating reduced signalling via the transcription factor HilA in the heterogeneous SPI-1 expression of these strains. The previously unrecognized strain heterogeneity in SPI-1 expression and invasiveness has important implications for studies of Salmonella infection.

ORCID iDs

Clark, Leann, Perrett, Charlotte A., Malt, Layla, Harward, Caryn, Humphrey, Suzanne ORCID logoORCID: https://orcid.org/0000-0002-9893-3209, Jepson, Katy A., Martinez-Argudo, Isabel, Carney, Laura J., La Ragione, Roberto M., Humphrey, Tom J. and Jepson, Mark A.;
CORE (COnnecting REpositories)