title: Expression of and secretion through the Aeromonas salmonicida type III secretion system.
abstract: Aeromonas salmonicida subsp. salmonicida is the aetiological agent of furunculosis, a disease of farmed and wild salmonids. The type III secretion system (TTSS) is one of the primary virulence factors in A. salmonicida. Using a combination of differential proteomic analysis and reverse transcriptase (RT)-PCR, it is shown that A. salmonicida A449 induces the expression of TTSS proteins at 28 degrees C, but not at its more natural growth temperature of 17 degrees C. More modest increases in expression occur at 24 degrees C. This temperature-induced up-regulation of the TTSS in A. salmonicida A449 occurs within 30 min of a growth temperature increase from 16 to 28 degrees C. Growth conditions such as low-iron, low pH, low calcium, growth within the peritoneal cavity of salmon and growth to high cell densities do not induce the expression of the TTSS in A. salmonicida A449. The only other known growth condition that induces expression of the TTSS is growth of the bacterium at 16 degrees C in salt concentrations ranging from 0.19 to 0.38 M NaCl. It is also shown that growth at 28 degrees C followed by exposure to low calcium results in the secretion of one of the TTSS effector proteins. This study presents a simple in vitro model for the expression of TTSS proteins in A. salmonicida.
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Roger O
authors.initials: RO
authors.lastname: Ebanks
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Leah C
authors.initials: LC
authors.lastname: Knickle
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Goguen
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Boyd
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Devanand M
authors.initials: DM
authors.lastname: Pinto
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Reith
authors.affiliation: National Research Council Canada - Institute for Marine Biosciences, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
authors.forename: Neil W
authors.initials: NW
authors.lastname: Ross
mesh_terms: D048409:Aeromonas salmonicida / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000494:pharmacology; D010529:Peritoneal Cavity / Q000382:microbiology; D010957:Plasmids; D021381:Protein Transport / Q000235:genetics; D020543:Proteome / Q000032:analysis; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020317:Salmo salar / Q000382:microbiology; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D014158:Transcription, Genetic; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D012329:RNA, Bacterial; D012333:RNA, Messenger; D037521:Virulence Factors; D012965:Sodium Chloride; D007501:Iron; D002118:Calcium