Loading...
Interactions of Bordetella pertussis adenylyl cyclase toxin CyaA with calmodulin mutants and calmodulin antagonists: Comparison with membranous adenylyl cyclase I
Schuler, Dominik Lubker, Carolin Lushington, Gerald H. Tang, Wei-Jen Shen, Yuequan Richter, Mark Seifert, Roland
Schuler, Dominik
Lubker, Carolin
Lushington, Gerald H.
Tang, Wei-Jen
Shen, Yuequan
Richter, Mark
Seifert, Roland
Citations
Altmetric:
Abstract
The adenylyl cyclase (AC) toxin CyaA from Bordetella pertussis constitutes an important virulence factor for the pathogenesis of whooping cough. CyaA is activated by calmodulin (CaM) and compromises host defense by excessive cAMP production. Hence, pharmacological modulation of the CyaA/CaM interaction could constitute a promising approach to treat whooping cough, provided that interactions of endogenous effector proteins with CaM are not affected. As a first step toward this ambitious goal we examined the interactions of CyaA with wild-type CaM and four CaM mutants in which most methionine residues were replaced by leucine residues and studied the effects of the CaM antagonists calmidazolium, trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). CyaA/CaM interaction was monitored by CaM-dependent fluorescence resonance energy transfer (FRET) between tryptophan residues in CyaA and 2′-(N-methylanthraniloyl)-3′-deoxy-adenosine 5′-triphosphate and catalytic activity. Comparison of the concentration/response curves of CaM and CaM mutants for FRET and catalysis revealed differences, suggesting a two-step activation mechanism of CyaA by CaM. Even in the absence of CaM, calmidazolium inhibited catalysis, and it did so according to a biphasic function. Trifluoperazine and W-7 did not inhibit FRET or catalysis. In contrast to CyaA, some CaM mutants were more efficacious than CaM at activating membranous AC isoform 1. The slope of CyaA activation by CaM was much steeper than of AC1 activation. Collectively, the two-step activation mechanism of CyaA by CaM offers opportunities for pharmacological intervention. The failure of classic CaM inhibitors to interfere with CyaA/CaM interactions and the different interactions of CaM mutants with CyaA and AC1 point to unique CyaA/CaM interactions.
Description
Date
2012-01-13
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Collections
Files
Loading...
richter_interactions.pdf
Adobe PDF, 1.49 MB
Research Projects
Organizational Units
Journal Issue
Keywords
Bordetella pertussis, Adenylyl cyclase, Calmodulin, Fluorescence spectroscopy, Calmodulin antagonists
Citation
Schuler, Dominik, Carolin Lübker, Gerald H. Lushington, Wei-Jen Tang, Yuequan Shen, Mark Richter, and Roland Seifert. "Interactions of Bordetella Pertussis Adenylyl Cyclase Toxin CyaA with Calmodulin Mutants and Calmodulin Antagonists: Comparison with Membranous Adenylyl Cyclase I." Biochemical Pharmacology 83.7 (2012): 839-48.