title: IglE is an outer membrane-associated lipoprotein essential for intracellular survival and murine virulence of type A Francisella tularensis.
abstract: IglE is a small, hypothetical protein encoded by the duplicated Francisella pathogenicity island (FPI). Inactivation of both copies of iglE rendered Francisella tularensis subsp. tularensis Schu S4 avirulent and incapable of intracellular replication, owing to an inability to escape the phagosome. This defect was fully reversed following single-copy expression of iglE in trans from attTn7 under the control of the Francisella rpsL promoter, thereby establishing that the loss of iglE, and not polar effects on downstream vgrG gene expression, was responsible for the defect. IglE is exported to the Francisella outer membrane as an ∼13.9-kDa lipoprotein, determined on the basis of a combination of selective Triton X-114 solubilization, radiolabeling with [(3)H]palmitic acid, and sucrose density gradient membrane partitioning studies. Lastly, a genetic screen using the iglE-null live vaccine strain resulted in the identification of key regions in the carboxyl terminus of IglE that are required for intracellular replication of Francisella tularensis in J774A.1 macrophages. Thus, IglE is essential for Francisella tularensis virulence. Our data support a model that likely includes protein-protein interactions at or near the bacterial cell surface that are unknown at present.
authors: Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors: Gregory T
authors: GT
authors: Robertson
authors: Robert
authors: R
authors: Child
authors: Christine
authors: C
authors: Ingle
authors: Jean
authors: J
authors: Celli
authors: Michael V
authors: MV
authors: Norgard
mesh_terms: D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D005260:Female; D005604:Francisella tularensis / Q000737:chemistry / Q000235:genetics / Q000472:pathogenicity*; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D044404:Genomic Islands; D008074:Lipoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D008970:Molecular Weight; D014406:Tularemia / Q000382:microbiology / Q000473:pathology*; D014774:Virulence; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D008074:Lipoproteins; D008565:Membrane Proteins; D037521:Virulence Factors
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