Calpain-Mediated Processing of Adenylate Cyclase Toxin Generates a Cytosolic Soluble Catalytically Active N-Terminal DomainReportar como inadecuado




Calpain-Mediated Processing of Adenylate Cyclase Toxin Generates a Cytosolic Soluble Catalytically Active N-Terminal Domain - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Bordetella pertussis, the whooping cough pathogen, secretes several virulence factors among which adenylate cyclase toxin ACT is essential for establishment of the disease in the respiratory tract. ACT weakens host defenses by suppressing important bactericidal activities of the phagocytic cells. Up to now, it was believed that cell intoxication by ACT was a consequence of the accumulation of abnormally high levels of cAMP, generated exclusively beneath the host plasma membrane by the toxin N-terminal catalytic adenylate cyclase AC domain, upon its direct translocation across the lipid bilayer. Here we show that host calpain, a calcium-dependent Cys-protease, is activated into the phagocytes by a toxin-triggered calcium rise, resulting in the proteolytic cleavage of the toxin N-terminal domain that releases a catalytically active -soluble AC-. The calpain-mediated ACT processing allows trafficking of the -soluble AC- domain into subcellular organella. At least two strategic advantages arise from this singular toxin cleavage, enhancing the specificity of action, and simultaneously preventing an indiscriminate activation of cAMP effectors throughout the cell. The present study provides novel insights into the toxin mechanism of action, as the calpain-mediated toxin processing would confer ACT the capacity for a space- and time-coordinated production of different cAMP -pools-, which would play different roles in the cell pathophysiology.



Autor: Kepa B. Uribe , Aitor Etxebarria , César Martín , Helena Ostolaza

Fuente: http://plos.srce.hr/



DESCARGAR PDF




Documentos relacionados