title: Transmembrane segments of complement receptor 3 do not participate in cytotoxic activities but determine receptor structure required for action of Bordetella adenylate cyclase toxin.
abstract: Adenylate cyclase toxin-hemolysin (CyaA, ACT or AC-Hly) of the whooping cough agent Bordetella pertussis penetrates phagocytes expressing the integrin complement receptor 3 (CR3, CD11b/CD18, α(M)β(2) or Mac-1). CyaA translocates its adenylate cyclase (AC) enzyme domain into cell cytosol and catalyzes unregulated conversion of ATP to cAMP, thereby subverting cellular signaling. In parallel, CyaA forms small cation-selective membrane pores that permeabilize cells for potassium efflux, contributing to cytotoxicity of CyaA and eventually provoking colloid-osmotic cell lysis. To investigate whether the single-pass α-helical transmembrane segments of CR3 subunits CD11b and CD18 do directly participate in AC domain translocation and/or pore formation by the toxin, we expressed in CHO cells variants of CR3 that contained artificial transmembrane segments, or lacked the transmembrane segment(s) at all. The results demonstrate that the transmembrane segments of CR3 are not directly involved in the cytotoxic activities of CyaA but serve for maintaining CR3 in a conformation that is required for efficient toxin binding and action.
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Wald
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43, Prague 2, Czech Republic.
authors.forename: Adriana
authors.initials: A
authors.lastname: Osickova
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Masin
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, 128 44 Prague 2, Czech Republic.
authors.forename: Petra M
authors.initials: PM
authors.lastname: Liskova
authors.affiliation: Institute of Analytical Chemistry of the CAS, v. v. i., Veveri 97, 602 00 Brno, Czech Republic.
authors.forename: Inga
authors.initials: I
authors.lastname: Petry-Podgorska
authors.affiliation: Institute of Analytical Chemistry of the CAS, v. v. i., Veveri 97, 602 00 Brno, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Matousek
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Sebo
authors.affiliation: Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20, Prague 4, Czech Republic osicka@biomed.cas.cz.
authors.forename: Radim
authors.initials: R
authors.lastname: Osicka
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry; D037361:Adenylate Cyclase Toxin / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001886:Bordetella pertussis / Q000378:metabolism*; D039481:CD11b Antigen / Q000235:genetics / Q000378:metabolism*; D018821:CD18 Antigens / Q000235:genetics / Q000378:metabolism*; D016466:CHO Cells; D002460:Cell Line; D003412:Cricetulus; D000242:Cyclic AMP / Q000096:biosynthesis; D006801:Humans; D016177:Macrophage-1 Antigen / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D010586:Phagocytes / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D037361:Adenylate Cyclase Toxin; D039481:CD11b Antigen; D018821:CD18 Antigens; C509295:ITGAM protein, human; D016177:Macrophage-1 Antigen; D000255:Adenosine Triphosphate; D000242:Cyclic AMP
keywords: CD11b/CD18; CyaA; ICP-MS; adenylate cyclase toxin; complement receptor 3; transmembrane segment