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Membrane-Active Properties of an Amphitropic Peptide from the CyaA Toxin Translocation Region
Communication

Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin

1
Cell, Molecular, and Structural Biology Program, Miami University, Oxford, OH 45056, USA
2
Department of Microbiology, Miami University, Oxford, OH 45056, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Alexandre Chenal
Toxins 2017, 9(12), 389; https://doi.org/10.3390/toxins9120389
Received: 8 November 2017 / Revised: 26 November 2017 / Accepted: 27 November 2017 / Published: 30 November 2017
(This article belongs to the Special Issue Adenylate Cyclase (CyaA) Toxin)
Site I inactivation of calmodulin (CaM) was used to examine the importance of aspartic acid 22 at position 3 in CaM calcium binding, protein folding, and activation of the Bordetella pertussis adenylate cyclase toxin domain (CyaA-ACD). NMR calcium titration experiments showed that site I in the CaM mutant (D22A) remained largely unperturbed, while sites II, III, and IV exhibited calcium-induced conformational changes similar to wild-type CaM (CaMWt). Circular dichroism analyses revealed that D22A had comparable α-helical content to CaMWt, and only modest differences in α-helical composition were detected between CaMWt-CyaA-ACD and D22A-CyaA-ACD complexes. However, the thermal stability of the D22A-CyaA-ACD complex was reduced, as compared to the CaMWt-CyaA-ACD complex. Moreover, CaM-dependent activity of CyaA-ACD decreased 87% in the presence of D22A. Taken together, our findings provide evidence that D22A engages CyaA-ACD, likely through C-terminal mediated binding, and that site I inactivation exerts functional effects through the modification of stabilizing interactions that occur between N-terminal CaM and CyaA-ACD. View Full-Text
Keywords: calcium; calmodulin; CyaA toxin; NMR calcium; calmodulin; CyaA toxin; NMR
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MDPI and ACS Style

Johns, C.W.; Finley, N.L. Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin. Toxins 2017, 9, 389. https://doi.org/10.3390/toxins9120389

AMA Style

Johns CW, Finley NL. Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin. Toxins. 2017; 9(12):389. https://doi.org/10.3390/toxins9120389

Chicago/Turabian Style

Johns, Christian W., and Natosha L. Finley 2017. "Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin" Toxins 9, no. 12: 389. https://doi.org/10.3390/toxins9120389

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