title: Characterization of secreted sphingosine-1-phosphate lyases required for virulence and intracellular survival of Burkholderia pseudomallei.
abstract: Sphingosine-1-phosphate (S1P), a bioactive sphingolipid metabolite, plays a critical role in the orchestration of immune responses. S1P levels within the mammalian host are tightly regulated, in part through the activity of S1P lyase (S1PL) which catalyses its irreversible degradation. Herein, we describe the identification and characterization of secreted S1PL orthologues encoded by the facultative intracellular bacteria Burkholderia pseudomallei and Burkholderia thailandensis. These bacterial orthologues exhibited S1PL enzymatic activity, functionally complemented an S1PL-deficient yeast strain and conferred resistance to the antimicrobial sphingolipid D-erythro-sphingosine. We report that secretion of these bacterial S1PLs is pH-dependent, and is observed during intracellular infection. S1PL-deficient mutants displayed impaired intracellular replication in murine macrophages (associated with an inability to evade the maturing phagosome) and were significantly attenuated in murine and larval infection models. Furthermore, treatment of Burkholderia-infected macrophages with either S1P or a selective agonist of S1P receptor 1 enhanced bacterial colocalisation with LAMP-1 and reduced their intracellular survival. In summary, our studies confirm bacterial-encoded S1PL as a critical virulence determinant of B. pseudomallei and B. thailandensis, further highlighting the pivotal role of S1P in host-pathogen interactions. In addition, our data suggest that S1P pathway modulators have potential for the treatment of intracellular infection.
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, UK.
authors.forename: Rafael
authors.initials: R
authors.lastname: Custódio
authors.affiliation: School of Chemistry, University of Edinburgh, UK.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: McLean
authors.affiliation: Microbiology, Defence Science and Technology Laboratory, Porton Down, UK.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Scott
authors.affiliation: School of Chemistry, University of Edinburgh, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lowther
authors.affiliation: School of Chemistry, University of Edinburgh, UK.
authors.forename: Amanda
authors.initials: A
authors.lastname: Kennedy
authors.affiliation: School of Chemistry, University of Edinburgh, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Clarke
authors.affiliation: School of Chemistry, University of Edinburgh, UK.
authors.forename: Dominic J
authors.initials: DJ
authors.lastname: Campopiano
authors.affiliation: Microbiology, Defence Science and Technology Laboratory, Porton Down, UK.|Marshall Centre for Infectious Diseases and Training, School of Pathology and Laboratory Medicine, University of Western Australia, WA 6009, Australia.
authors.forename: Mitali
authors.initials: M
authors.lastname: Sarkar-Tyson
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, UK.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Brown
mesh_terms: D000446:Aldehyde-Lyases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D016957:Burkholderia pseudomallei / Q000378:metabolism; D054884:Host-Pathogen Interactions; D008246:Lysophospholipids / Q000235:genetics / Q000378:metabolism*; D052118:Lysosomal-Associated Membrane Protein 1; D008264:Macrophages; D051379:Mice; D013107:Sphingolipids / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000502:physiology; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D008246:Lysophospholipids; D052118:Lysosomal-Associated Membrane Protein 1; D013107:Sphingolipids; D037521:Virulence Factors; C060506:sphingosine 1-phosphate; D000446:Aldehyde-Lyases; C022649:sphingosine 1-phosphate lyase (aldolase); D013110:Sphingosine