Adenylate Cyclase Toxin promotes bacterial internalisation into non phagocytic cells.
Bordetella pertussis causes whooping cough, a respiratory infectious disease that is the fifth largest cause of vaccine-preventable death in infants. Though historically considered an extracellular pathogen, this bacterium has been detected both in vitro and in vivo inside phagocytic and non-phagocytic cells. However the precise mechanism used by B. pertussis for cell entry, or the putative bacterial factors involved, are not fully elucidated. Here we find that adenylate cyclase toxin (ACT), one of the important toxins of B. pertussis, is sufficient to promote bacterial internalisation into non-phagocytic cells. After characterization of the entry route we show that uptake of "toxin-coated bacteria" proceeds via a clathrin-independent, caveolae-dependent entry pathway, allowing the internalised bacteria to survive within the cells. Intracellular bacteria were found inside non-acidic endosomes with high sphingomyelin and cholesterol content, or "free" in the cytosol of the invaded cells, suggesting that the ACT-induced bacterial uptake may not proceed through formation of late endolysosomes. Activation of Tyr kinases and toxin-induced Ca(2+)-influx are essential for the entry process. We hypothesize that B. pertussis might use ACT to activate the endocytic machinery of non-phagocytic cells and gain entry into these cells, in this way evading the host immune system.
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
César
C
Martín
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Asier
A
Etxaniz
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Kepa B
KB
Uribe
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Aitor
A
Etxebarria
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
David
D
González-Bullón
Departamento de Biología Celular, Facultad de Medicina, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Jon
J
Arlucea
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Félix M
FM
Goñi
Departamento de Biología Celular, Facultad de Medicina, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Juan
J
Aréchaga
Departamento de Bioquímica y Biología Molecular and Unidad de Biofísica (CSIC, UPV/EHU), Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain.
Helena
H
Ostolaza
D000199:Actins / Q000378:metabolism; D037361:Adenylate Cyclase Toxin / Q000378:metabolism*; D000818:Animals; D001886:Bordetella pertussis / Q000502:physiology*; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival; D003412:Cricetulus; D011992:Endosomes / Q000382:microbiology; D006801:Humans; D010586:Phagocytes / Q000382:microbiology; D014917:Whooping Cough / Q000378:metabolism / Q000382:microbiology
D000199:Actins; D037361:Adenylate Cyclase Toxin; D002118:Calcium