title: Subcellular discharge of a serine protease mediates release of invasive malaria parasites from host erythrocytes.
abstract: The most virulent form of malaria is caused by waves of replication of blood stages of the protozoan pathogen Plasmodium falciparum. The parasite divides within an intraerythrocytic parasitophorous vacuole until rupture of the vacuole and host-cell membranes releases merozoites that invade fresh erythrocytes to repeat the cycle. Despite the importance of merozoite egress for disease progression, none of the molecular factors involved are known. We report that, just prior to egress, an essential serine protease called PfSUB1 is discharged from previously unrecognized parasite organelles (termed exonemes) into the parasitophorous vacuole space. There, PfSUB1 mediates the proteolytic maturation of at least two essential members of another enzyme family called SERA. Pharmacological blockade of PfSUB1 inhibits egress and ablates the invasive capacity of released merozoites. Our findings reveal the presence in the malarial parasitophorous vacuole of a regulated, PfSUB1-mediated proteolytic processing event required for release of viable parasites from the host erythrocyte.
authors: Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK.
authors: Sharon
authors: S
authors: Yeoh
authors: Rebecca A
authors: RA
authors: O'Donnell
authors: Konstantinos
authors: K
authors: Koussis
authors: Anton R
authors: AR
authors: Dluzewski
authors: Keith H
authors: KH
authors: Ansell
authors: Simon A
authors: SA
authors: Osborne
authors: Fiona
authors: F
authors: Hackett
authors: Chrislaine
authors: C
authors: Withers-Martinez
authors: Graham H
authors: GH
authors: Mitchell
authors: Lawrence H
authors: LH
authors: Bannister
authors: Justin S
authors: JS
authors: Bryans
authors: Catherine A
authors: CA
authors: Kettleborough
authors: Michael J
authors: MJ
authors: Blackman
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism / Q000502:physiology; D004912:Erythrocytes / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008018:Life Cycle Stages; D008288:Malaria / Q000097:blood / Q000469:parasitology*; D008954:Models, Biological; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000472:pathogenicity / Q000648:ultrastructure; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D034101:Sporozoites / Q000502:physiology; D013381:Subtilisins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D014617:Vacuoles / Q000469:parasitology
chemical_list: D000953:Antigens, Protozoan; D015800:Protozoan Proteins; C480167:serine repeat antigen 5, Plasmodium falciparum; D013381:Subtilisins; C403176:subtilisin-like protease 1, Plasmodium falciparum