Fiser, Radovan and Masín, Jirí and Basler, Marek and Krusek, Jan and Spuláková, Veronika and Konopásek, Ivo and Sebo, Peter. (2007) Third activity of Bordetella adenylate cyclase (AC) toxin-hemolysin. Membrane translocation of AC domain polypeptide promotes calcium influx into CD11b+ monocytes independently of the catalytic and hemolytic activities. Journal of Biological Chemistry, 282 (5). pp. 2808-2820.
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Official URL: http://edoc.unibas.ch/49548/
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Abstract
The Bordetella adenylate cyclase toxin-hemolysin (CyaA) targets phagocytes expressing the alpha(M)beta2 integrin (CD11b/CD18), permeabilizes their membranes by forming small cation-selective pores, and delivers into cells a calmodulin-activated adenylate cyclase (AC) enzyme that dissipates cytosolic ATP into cAMP. We describe here a third activity of CyaA that yields elevation of cytosolic calcium concentration ([Ca2+]i) in target cells. The CyaA-mediated [Ca2+]i increase in CD11b+ J774A.1 monocytes was inhibited by extracellular La3+ ions but not by nifedipine, SK&F 96365, flunarizine, 2-aminoethyl diphenylborinate, or thapsigargin, suggesting that influx of Ca2+ into cells was not because of receptor signaling or opening of conventional calcium channels by cAMP. Compared with intact CyaA, a CyaA-AC- toxoid unable to generate cAMP promoted a faster, albeit transient, elevation of [Ca2+]i. This was not because of cell permeabilization by the CyaA hemolysin pores, because a mutant exhibiting a strongly enhanced pore-forming activity (CyaA-E509K/E516K), but unable to deliver the AC domain into cells, was also unable to elicit a [Ca2+]i increase. Further mutations interfering with AC translocation into cells, such as proline substitutions of glutamate residues 509 or 570 or deletion of the AC domain as such, reduced or ablated the [Ca2+]i-elevating capacity of CyaA. Moreover, structural alterations within the AC domain, because of insertion of various oligopeptides, differently modulated the kinetics and extent of Ca2+ influx elicited by the respective AC- toxoids. Hence, the translocating AC polypeptide itself appears to participate in formation of a novel type of membrane path for calcium ions, contributing to action of CyaA in an unexpected manner.
Faculties and Departments: | 05 Faculty of Science > Departement Biozentrum > Infection Biology > Infection Biology (Basler) |
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UniBasel Contributors: | Basler, Marek |
Item Type: | Article, refereed |
Article Subtype: | Research Article |
Publisher: | American Society for Biochemistry and Molecular Biology |
ISSN: | 0021-9258 |
e-ISSN: | 1083-351X |
Note: | Publication type according to Uni Basel Research Database: Journal article |
Identification Number: |
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Last Modified: | 28 Nov 2017 08:17 |
Deposited On: | 28 Nov 2017 08:17 |
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