Calmodulin fishing with a structurally disordered bait triggers CyaA catalysis.
PLoS Biol
; 15(12): e2004486, 2017 12.
Article
em En
| MEDLINE
| ID: mdl-29287065
ABSTRACT
Once translocated into the cytosol of target cells, the catalytic domain (AC) of the adenylate cyclase toxin (CyaA), a major virulence factor of Bordetella pertussis, is potently activated by binding calmodulin (CaM) to produce supraphysiological levels of cAMP, inducing cell death. Using a combination of small-angle X-ray scattering (SAXS), hydrogen/deuterium exchange mass spectrometry (HDX-MS), and synchrotron radiation circular dichroism (SR-CD), we show that, in the absence of CaM, AC exhibits significant structural disorder, and a 75-residue-long stretch within AC undergoes a disorder-to-order transition upon CaM binding. Beyond this local folding, CaM binding induces long-range allosteric effects that stabilize the distant catalytic site, whilst preserving catalytic loop flexibility. We propose that the high enzymatic activity of AC is due to a tight balance between the CaM-induced decrease of structural flexibility around the catalytic site and the preservation of catalytic loop flexibility, allowing for fast substrate binding and product release. The CaM-induced dampening of AC conformational disorder is likely relevant to other CaM-activated enzymes.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Bordetella pertussis
/
Calmodulina
/
Toxina Adenilato Ciclase
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
PLoS Biol
Assunto da revista:
BIOLOGIA
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
França