Almost half of the RTX domain is dispensable for complement receptor 3 binding and cell-invasive activity of the Bordetella adenylate cyclase toxin.

Autor: Espinosa-Vinals CA; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic; University of Chemistry and Technology, Prague, Prague, Czech Republic., Masin J; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic., Holubova J; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic., Stanek O; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic., Jurnecka D; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic., Osicka R; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic., Sebo P; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic. Electronic address: sebo@biomed.cas.cz., Bumba L; Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic. Electronic address: bumba@biomed.cas.cz.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2021 Jul; Vol. 297 (1), pp. 100833. Date of Electronic Publication: 2021 May 26.
DOI: 10.1016/j.jbc.2021.100833
Abstrakt: The whooping cough agent Bordetella pertussis secretes an adenylate cyclase toxin (CyaA) that through its large carboxy-proximal Repeat-in-ToXin (RTX) domain binds the complement receptor 3 (CR3). The RTX domain consists of five blocks (I-V) of characteristic glycine and aspartate-rich nonapeptides that fold into five Ca 2+ -loaded parallel β-rolls. Previous work indicated that the CR3-binding structure comprises the interface of β-rolls II and III. To test if further portions of the RTX domain contribute to CR3 binding, we generated a construct with the RTX block II/III interface (CyaA residues 1132-1294) linked directly to the C-terminal block V fragment bearing the folding scaffold (CyaA residues 1562-1681). Despite deletion of 267 internal residues of the RTX domain, the Ca 2+ -driven folding of the hybrid block III/V β-roll still supported formation of the CR3-binding structure at the interface of β-rolls II and III. Moreover, upon stabilization by N- and C-terminal flanking segments, the block III/V hybrid-comprising constructs competed with CyaA for CR3 binding and induced formation of CyaA toxin-neutralizing antibodies in mice. Finally, a truncated CyaAΔ 1295-1561 toxin bound and penetrated erythrocytes and CR3-expressing cells, showing that the deleted portions of RTX blocks III, IV, and V (residues 1295-1561) were dispensable for CR3 binding and for toxin translocation across the target cell membrane. This suggests that almost a half of the RTX domain of CyaA is not involved in target cell interaction and rather serves the purpose of toxin secretion.
Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article.
(Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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