title: Bacterial RTX toxins allow acute ATP release from human erythrocytes directly through the toxin pore.
abstract: ATP is as an extracellular signaling molecule able to amplify the cell lysis inflicted by certain bacterial toxins including the two RTX toxins α-hemolysin (HlyA) from Escherichia coli and leukotoxin A (LtxA) from Aggregatibacter actinomycetemcomitans. Inhibition of P2X receptors completely blocks the RTX toxin-induced hemolysis over a larger concentration range. It is, however, at present not known how the ATP that provides the amplification is released from the attacked cells. Here we show that both HlyA and LtxA trigger acute release of ATP from human erythrocytes that preceded and were not caused by cell lysis. This early ATP release did not occur via previously described ATP-release pathways in the erythrocyte. Both HlyA and LtxA were capable of triggering ATP release in the presence of the pannexin 1 blockers carbenoxolone and probenecid, and the HlyA-induced ATP release was found to be similar in erythrocytes from pannexin 1 wild type and knock-out mice. Moreover, the voltage-dependent anion channel antagonist TRO19622 had no effect on ATP release by either of the toxins. Finally, we showed that both HlyA and LtxA were able to release ATP from ATP-loaded lipid (1-palmitoyl-2-oleoyl-phosphatidylcholine) vesicles devoid of any erythrocyte channels or transporters. Again we were able to show that this happened in a non-lytic fashion, using calcein-containing vesicles as controls. These data show that both toxins incorporate into lipid vesicles and allow ATP to be released. We suggest that both toxins cause acute ATP release by letting ATP pass the toxin pores in both human erythrocytes and artificial membranes.
authors.affiliation: From the Department of Biomedicine, MEMBRANES, and.
authors.forename: Marianne
authors.initials: M
authors.lastname: Skals
authors.affiliation: From the Department of Biomedicine, MEMBRANES, and.
authors.forename: Randi G
authors.initials: RG
authors.lastname: Bjaelde
authors.affiliation: Department of Dentistry.
authors.forename: Jesper
authors.initials: J
authors.lastname: Reinholdt
authors.affiliation: From the Department of Biomedicine.
authors.forename: Knud
authors.initials: K
authors.lastname: Poulsen
authors.affiliation: the Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Center for Insoluble Proteins (inSPIN), Aarhus University, Aarhus C 8000, Denmark.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Vad
authors.affiliation: the Department of Molecular Biology and Genetics, Interdisciplinary Nanoscience Center (iNANO), Center for Insoluble Proteins (inSPIN), Aarhus University, Aarhus C 8000, Denmark.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Otzen
authors.affiliation: From the Department of Biomedicine, MEMBRANES, and.
authors.forename: Jens
authors.initials: J
authors.lastname: Leipziger
authors.affiliation: From the Department of Biomedicine, MEMBRANES, and hp@fi.au.dk.
authors.forename: Helle A
authors.initials: HA
authors.lastname: Praetorius
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D016976:Aggregatibacter actinomycetemcomitans; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000494:pharmacology*; D017630:Connexins / Q000172:deficiency / Q000235:genetics; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000494:pharmacology*; D055786:Gene Knockout Techniques; D006454:Hemoglobins / Q000378:metabolism; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008567:Membranes, Artificial; D051379:Mice; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000235:genetics; D010713:Phosphatidylcholines / Q000378:metabolism; D016062:Porosity
chemical_list: D001426:Bacterial Proteins; D017630:Connexins; D029968:Escherichia coli Proteins; D006454:Hemoglobins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli; D008567:Membranes, Artificial; D009419:Nerve Tissue Proteins; C503631:Panx1 protein, mouse; D010713:Phosphatidylcholines; C102677:lktA protein, bacteria; D000255:Adenosine Triphosphate; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: ATP Release; Bacterial Toxin; Erythrocyte; Escherichia coli (E. coli); Hemolysin; Hemolysis; Leukotoxin; P2-receptors; Pannexin; Phospholipid Vesicle