title: The Salmonella SPI1 effector SopB stimulates nitric oxide production long after invasion.
abstract: The ability of Salmonella enterica to invade and replicate within host cells depends on two type III secretion systems (TTSSs) encoded on pathogenicity islands 1 and 2 (SPI1 and SPI2). The current paradigm holds that these systems translocate two classes of effectors that operate sequentially and independently. In essence, the SPI1 TTSS mediates early events (i.e. invasion) whereas the SPI2 TTSS mediates post-invasion processes (i.e. replication, vacuole maturation). Contrary to this model, we have found in infected macrophages that a SPI1 effector, SopB/SigD, increased inducible nitric oxide synthase levels and nitric oxide production, host cell process previously known only to be a target of the SPI2 TTSS. Furthermore, SopB protein and message persist many hours after invasion. Our findings reveal an unanticipated potential for dialogue between the SPI1 and SPI2 TTSS and the host cell response.
authors.affiliation: Laboratory of Intracellular Parasites, National Institutes of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, MT 59840, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Drecktrah
authors.forename: Leigh A
authors.initials: LA
authors.lastname: Knodler
authors.forename: Kendal
authors.initials: K
authors.lastname: Galbraith
authors.forename: Olivia
authors.initials: O
authors.lastname: Steele-Mortimer
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D044404:Genomic Islands / Q000235:genetics / Q000502:physiology; D008264:Macrophages / Q000276:immunology / Q000382:microbiology*; D051379:Mice; D009569:Nitric Oxide / Q000032:analysis / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D019779:Salmonella enterica / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; C489224:SopB protein, Salmonella