Acanthamoeba castellanii Proteases are Capable of Degrading Iron-Binding Proteins as a Possible Mechanism of Pathogenicity.
Acanthamoeba castellanii, a free-living amoeba, is an amphizoic organism that can behave as an opportunistic pathogen, causing granulomatous amoebic encephalitis in immunocompromised patients or infecting immunocompetent individuals via cutaneous lesions, sinusoidal infections, or amoebic keratitis. Therefore, this amoeba could be in contact with different iron-binding proteins, such as lactoferrin in tears and mucosa and transferrin and hemoglobin in blood. Iron is a vital and necessary element for host metabolism but also for parasite survival. Accordingly, parasites have developed iron uptake mechanisms, one of which is the utilization of proteases to degrade host iron-binding proteins. In this work, we performed a partial biochemical characterization of A. castellanii proteases at different pHs and utilizing protease inhibitors with 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and copolymerized with different iron-binding proteins. We describe for the first time the presence of several cysteine proteases in a total A. castellanii crude extract and in conditioned culture medium precipitated with ethanol. These amoebic peptidases degraded human holo-lactoferrin, holo-transferrin, hemoglobin, and horse spleen ferritin; some of these proteases were substrate specific, and others degraded multiple substrates. These proteases could be considered virulence factors that promote iron acquisition from the host.
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, 07360, México, Distrito Federal, México.
Gerardo
G
Ramírez-Rico
Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, 07360, México, Distrito Federal, México.
Moisés
M
Martínez-Castillo
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, 07360, México, Distrito Federal, México.
Mireya
M
de la Garza
Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, 07360, México, Distrito Federal, México.
Mineko
M
Shibayama
Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, 07360, México, Distrito Federal, México.
Jesús
J
Serrano-Luna
D048248:Acanthamoeba castellanii / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism / Q000472:pathogenicity*; D000818:Animals; D017077:Culture Media, Conditioned; D057056:Cysteine Proteases / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005293:Ferritins / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006736:Horses; D006801:Humans; D006863:Hydrogen-Ion Concentration; D033862:Iron-Binding Proteins / Q000378:metabolism*; D007781:Lactoferrin / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D014168:Transferrin / Q000378:metabolism; D014774:Virulence
D017077:Culture Media, Conditioned; D006454:Hemoglobins; D033862:Iron-Binding Proteins; D011480:Protease Inhibitors; D014168:Transferrin; C492629:hololactoferrin, human; C110714:holotransferrin; D005293:Ferritins; D057056:Cysteine Proteases; D007781:Lactoferrin
Cysteine proteases; ferritin; free-living amoebae; hemoglobin; holo-lactoferrin; transferrin; virulence