Protein kinase a dependent phosphorylation of apical membrane antigen 1 plays an important role in erythrocyte invasion by the malaria parasite.
Apicomplexan parasites are obligate intracellular parasites that infect a variety of hosts, causing significant diseases in livestock and humans. The invasive forms of the parasites invade their host cells by gliding motility, an active process driven by parasite adhesion proteins and molecular motors. A crucial point during host cell invasion is the formation of a ring-shaped area of intimate contact between the parasite and the host known as a tight junction. As the invasive zoite propels itself into the host-cell, the junction moves down the length of the parasite. This process must be tightly regulated and signalling is likely to play a role in this event. One crucial protein for tight-junction formation is the apical membrane antigen 1 (AMA1). Here we have investigated the phosphorylation status of this key player in the invasion process in the human malaria parasite Plasmodium falciparum. We show that the cytoplasmic tail of P. falciparum AMA1 is phosphorylated at serine 610. We provide evidence that the enzyme responsible for serine 610 phosphorylation is the cAMP regulated protein kinase A (PfPKA). Importantly, mutation of AMA1 serine 610 to alanine abrogates phosphorylation of AMA1 in vivo and dramatically impedes invasion. In addition to shedding unexpected new light on AMA1 function, this work represents the first time PKA has been implicated in merozoite invasion.
Macfarlane Burnet Institute for Medical Research & Public Health, Melbourne, Victoria, Australia.
Kerstin
K
Leykauf
Moritz
M
Treeck
Paul R
PR
Gilson
Thomas
T
Nebl
Thomas
T
Braulke
Alan F
AF
Cowman
Tim W
TW
Gilberger
Brendan S
BS
Crabb
D000595:Amino Acid Sequence; D000953:Antigens, Protozoan / Q000378:metabolism*; D015153:Blotting, Western; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004912:Erythrocytes / Q000378:metabolism* / Q000469:parasitology*; D006801:Humans; D047468:Immunoprecipitation; D016778:Malaria, Falciparum / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010963:Plasmodium falciparum / Q000378:metabolism / Q000472:pathogenicity*; D015800:Protozoan Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C090077:apical membrane antigen I, Plasmodium; D017868:Cyclic AMP-Dependent Protein Kinases