Characterisation of proteins extracted from the surface of Salmonella Typhimurium grown under SPI-2-inducing conditions by LC-ESI/MS/MS sequencing.
Salmonella enterica has two pathogenicity islands encoding separate type three secretion systems (T3SS). Proteins secreted through these systems facilitate invasion and survival. After entry, Salmonella reside within a membrane bound vacuole, the Salmonella containing vacuole (SCV), where translocation of a second set of effectors by the Salmonella pathogenicity island 2 (SPI-2) T3SS is initiated. SPI-2 secretion in vitro can be induced by conditions that mimic the Salmonella containing vacuole. Utilising high-throughput mass spectrometry, we mapped the surface-attached proteome of S. Typhimurium SL1344 grown in vitro under SPI-2-inducing conditions and identified 108 proteins; using secretion signal prediction software, 43% of proteins identified contained a signal sequence. Of these proteins, 13 were known secreted effector proteins including SPI-2 effector proteins SseB, SseC, SseD, SseL, PipB2 and SteC, although surprisingly five were SPI-1 proteins, SipA, SipB, SipC, SipD and SopD, while 2 proteins SteA and SlrP are secreted by both T3SSs. This is the first in vitro study to demonstrate dual secretion of SPI-1 and SPI-2 proteins by S. Typhimurium and demonstrates the potential of high-throughput LC-ESI/MS/MS sequencing for the identification of novel proteins, providing a platform for subsequent comparative proteomic analysis, which should greatly assist understanding of the pathogenesis and inherent variation between serovars of Salmonella and ultimately help towards development of novel control strategies.
Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Glasgow, UK.
Aileen E
AE
Sherry
Neil F
NF
Inglis
Andy
A
Stevenson
Douglas
D
Fraser-Pitt
Paul
P
Everest
David G E
DG
Smith
Mark
M
Roberts
D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002853:Chromatography, Liquid; D008565:Membrane Proteins / Q000378:metabolism*; D012480:Salmonella Infections / Q000378:metabolism* / Q000382:microbiology; D012486:Salmonella typhimurium / Q000378:metabolism*; D015398:Signal Transduction; D021241:Spectrometry, Mass, Electrospray Ionization
D001426:Bacterial Proteins; D008565:Membrane Proteins; C440638:SPI-2 protein, Salmonella