The Clp chaperones and proteases of the human malaria parasite Plasmodium falciparum.
The Clp chaperones and proteases play an important role in protein homeostasis in the cell. They are highly conserved across prokaryotes and found also in the mitochondria of eukaryotes and the chloroplasts of plants. They function mainly in the disaggregation, unfolding and degradation of native as well as misfolded proteins. Here, we provide a comprehensive analysis of the Clp chaperones and proteases in the human malaria parasite Plasmodium falciparum. The parasite contains four Clp ATPases, which we term PfClpB1, PfClpB2, PfClpC and PfClpM. One PfClpP, the proteolytic subunit, and one PfClpR, which is an inactive version of the protease, were also identified. Expression of all Clp chaperones and proteases was confirmed in blood-stage parasites. The proteins were localized to the apicoplast, a non-photosynthetic organelle that accommodates several important metabolic pathways in P. falciparum, with the exception of PfClpB2 (also known as Hsp101), which was found in the parasitophorous vacuole. Both PfClpP and PfClpR form mostly homoheptameric rings as observed by size-exclusion chromatography, analytical ultracentrifugation and electron microscopy. The X-ray structure of PfClpP showed the protein as a compacted tetradecamer similar to that observed for Streptococcus pneumoniae and Mycobacterium tuberculosis ClpPs. Our data suggest the presence of a ClpCRP complex in the apicoplast of P. falciparum.
El Bakkouri
Majida
M
Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
Pow
Andre
A
Mulichak
Anne
A
Cheung
Kevin L Y
KL
Artz
Jennifer D
JD
Amani
Mehrnaz
M
Fell
Stuart
S
de Koning-Ward
Tania F
TF
Goodman
C Dean
CD
McFadden
Geoffrey I
GI
Ortega
Joaquin
J
Hui
Raymond
R
Houry
Walid A
WA
D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D049071:Endopeptidase Clp / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017125:Genes, Protozoan; D006801:Humans; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015388:Organelles / Q000378:metabolism; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance
D018832:Molecular Chaperones; D015800:Protozoan Proteins; D049071:Endopeptidase Clp