Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis.
We report the identification of the product of the Plasmodium falciparum Pf11-1 gene and demonstrate that it is a gametocyte-specific protein that has a potential role in the rupture of the host erythrocyte and emergence of the gametes (gametogenesis). The Pf11-1 gene is a large locus (30 kb) whose sequence predicts a glutamic acid-rich polypeptide. Our identification of the Pf11-1 gene product as gametocyte specific was greatly facilitated by the isolation of a mutant parasite clone in which greater than 90% of the Pf11-1 gene was deleted. Molecular analysis of the mutant locus suggests that the underlying genetic mechanism is chromosome breakage and subsequent healing by the addition of telomere repeats. PCR-based analysis showed that similar DNA rearrangements occur commonly in small subpopulations of most laboratory strains, suggesting that the Pf11-1 locus represents a fragile chromosome region. Northern blot analysis demonstrates that a large Pf11-1 gene-specific transcript (much greater than 10 kb) is present in gametocytes but not in asexual blood stage parasites. The Pf11-1 protein was localized by electron microscopy to granules in the cytoplasm of gametocytes adjacent to the membrane of the parasitophorous vacuole. Following in vitro stimulation of gametogenesis, the Pf11-1 protein was found in the membrane of lysed erythrocytes, suggesting a role for Pf11-1 in erythrocyte rupture within the mosquito gut.
Scherf
A
A
Unité de Parasitologie Expérimentale, CNRS URA 361, Institut Pasteur, Paris, France.
Carter
R
R
Petersen
C
C
Alano
P
P
Nelson
R
R
Aikawa
M
M
Mattei
D
D
Pereira da Silva
L
L
Leech
J
J
D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D025063:Chromosome Disorders; D002874:Chromosome Mapping; D002875:Chromosomes / Q000648:ultrastructure; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis / Q000235:genetics; D015342:DNA Probes; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000469:parasitology; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009154:Mutation; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D012098:Reproduction / Q000235:genetics
D000911:Antibodies, Monoclonal; D015342:DNA Probes; D004247:DNA