Autophagy-related Atg8 localizes to the apicoplast of the human malaria parasite Plasmodium falciparum.
Autophagy is a membrane-mediated degradation process, which is governed by sequential functions of Atg proteins. Although Atg proteins are highly conserved in eukaryotes, protozoa possess only a partial set of Atg proteins. Nonetheless, almost all protozoa have the complete factors belonging to the Atg8 conjugation system, namely, Atg3, Atg4, Atg7, and Atg8. Here, we report the biochemical properties and subcellular localization of the Atg8 protein of the human malaria parasite Plasmodium falciparum (PfAtg8). PfAtg8 is expressed during intra-erythrocytic development and associates with membranes likely as a lipid-conjugated form. Fluorescence microscopy and immunoelectron microscopy show that PfAtg8 localizes to the apicoplast, a four membrane-bound non-photosynthetic plastid. Autophagosome-like structures are not observed in the erythrocytic stages. These data suggest that, although Plasmodium parasites have lost most Atg proteins during evolution, they use the Atg8 conjugation system for the unique organelle, the apicoplast.
Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo, Japan.
Kei
K
Kitamura
Chieko
C
Kishi-Itakura
Takafumi
T
Tsuboi
Shigeharu
S
Sato
Kiyoshi
K
Kita
Nobuo
N
Ohta
Noboru
N
Mizushima
D000595:Amino Acid Sequence; D000962:Antimalarials / Q000494:pharmacology; D001343:Autophagy; D002462:Cell Membrane / Q000378:metabolism; D002738:Chloroquine / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology; D006801:Humans; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018087:Plastids / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D000962:Antimalarials; D015800:Protozoan Proteins; D002738:Chloroquine