title: ATP Depletion Via Mitochondrial F1F0 Complex by Lethal Factor is an Early Event in B. Anthracis-Induced Sudden Cell Death.
abstract: Bacillus anthracis' primary virulence factor is a tripartite anthrax toxin consisting of edema factor (EF), lethal factor (LF) and protective antigen (PA). In complex with PA, EF and LF are internalized via receptor-mediated endocytosis. EF is a calmodulin-dependent adenylate cyclase that induces tissue edema. LF is a zinc-metalloprotease that cleaves members of mitogen-activated protein kinase kinases. Lethal toxin (LT: PA plus LF)-induced death of macrophages is primarily attributed to expression of the sensitive Nalp1b allele, inflammasome formation and activation of caspase-1, but early events that initiate these processes are unknown. Here we provide evidence that an early essential event in pyroptosis of alveolar macrophages is LF-mediated depletion of cellular ATP. The underlying mechanism involves interaction of LF with F1F0-complex gamma and beta subunits leading to increased ATPase activity in mitochondria. In support, mitochondrial DNA-depleted MH-S cells have decreased F1F0 ATPase activity due to the lack of F06 and F08 polypeptides and show increased resistance to LT. We conclude that ATP depletion is an important early event in LT-induced sudden cell death and its prevention increases survival of toxin-sensitive cells.
authors.affiliation: Medical Service Corps, Diagnostic System Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702.
authors.forename: Mitchell W
authors.initials: MW
authors.lastname: Woodberry
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Leopoldo
authors.initials: L
authors.lastname: Aguilera-Aguirre
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Attila
authors.initials: A
authors.lastname: Bacsi
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Chopra
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kurosky
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Johnny W
authors.initials: JW
authors.lastname: Peterson
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555.
authors.forename: Istvan
authors.initials: I
authors.lastname: Boldogh
keywords: F1F0 ATPase; anthrax lethal factor; mitochondria; pyroptosis