Lineage-specific expansion of proteins exported to erythrocytes in malaria parasites.
BACKGROUND
The apicomplexan parasite Plasmodium falciparum causes the most severe form of malaria in humans. After invasion into erythrocytes, asexual parasite stages drastically alter their host cell and export remodeling and virulence proteins. Previously, we have reported identification and functional analysis of a short motif necessary for export of proteins out of the parasite and into the red blood cell.


RESULTS
We have developed software for the prediction of exported proteins in the genus Plasmodium, and identified exported proteins conserved between malaria parasites infecting rodents and the two major causes of human malaria, P. falciparum and P. vivax. This conserved 'exportome' is confined to a few subtelomeric chromosomal regions in P. falciparum and the synteny of these and surrounding regions is conserved in P. vivax. We have identified a novel gene family PHIST (for Plasmodium helical interspersed subtelomeric family) that shares a unique domain with 72 paralogs in P. falciparum and 39 in P. vivax; however, there is only one member in each of the three species studied from the P. berghei lineage.


CONCLUSIONS
These data suggest radiation of genes encoding remodeling and virulence factors from a small number of loci in a common Plasmodium ancestor, and imply a closer phylogenetic relationship between the P. vivax and P. falciparum lineages than previously believed. The presence of a conserved 'exportome' in the genus Plasmodium has important implications for our understanding of both common mechanisms and species-specific differences in host-parasite interactions, and may be crucial in developing novel antimalarial drugs to this infectious disease.
Sargeant
Tobias J
TJ
The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3050, Australia. sarjeant@wehi.edu.au
Marti
Matthias
M
Caler
Elisabet
E
Carlton
Jane M
JM
Simpson
Ken
K
Speed
Terence P
TP
Cowman
Alan F
AF
D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D004912:Erythrocytes / Q000469:parasitology*; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood; D005810:Multigene Family; D016366:Open Reading Frames; D010963:Plasmodium falciparum / Q000235:genetics*; D015800:Protozoan Proteins / Q000097:blood* / Q000235:genetics*; D012984:Software
D015800:Protozoan Proteins