title: The Clp chaperones and proteases of the human malaria parasite Plasmodium falciparum.
abstract: 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.
authors.affiliation: Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
authors.forename: Majida
authors.initials: M
authors.lastname: El Bakkouri
authors.forename: Andre
authors.initials: A
authors.lastname: Pow
authors.forename: Anne
authors.initials: A
authors.lastname: Mulichak
authors.forename: Kevin L Y
authors.initials: KL
authors.lastname: Cheung
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Artz
authors.forename: Mehrnaz
authors.initials: M
authors.lastname: Amani
authors.forename: Stuart
authors.initials: S
authors.lastname: Fell
authors.forename: Tania F
authors.initials: TF
authors.lastname: de Koning-Ward
authors.forename: C Dean
authors.initials: CD
authors.lastname: Goodman
authors.forename: Geoffrey I
authors.initials: GI
authors.lastname: McFadden
authors.forename: Joaquin
authors.initials: J
authors.lastname: Ortega
authors.forename: Raymond
authors.initials: R
authors.lastname: Hui
authors.forename: Walid A
authors.initials: WA
authors.lastname: Houry
mesh_terms: 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
chemical_list: D018832:Molecular Chaperones; D015800:Protozoan Proteins; D049071:Endopeptidase Clp