title: Structure of a Plasmodium falciparum PfEMP1 rosetting domain reveals a role for the N-terminal segment in heparin-mediated rosette inhibition.
abstract: The human malaria parasite Plasmodium falciparum can cause infected red blood cells (iRBC) to form rosettes with uninfected RBC, a phenotype associated with severe malaria. Rosetting is mediated by a subset of the Plasmodium falciparum membrane protein 1 (PfEMP1) variant adhesins expressed on the infected host-cell surface. Heparin and other sulfated oligosaccharides, however, can disrupt rosettes, suggesting that therapeutic approaches to this form of severe malaria are feasible. We present a structural and functional study of the N-terminal domain of PfEMP1 from the VarO variant comprising the N-terminal segment (NTS) and the first DBL domain (DBL1α(1)), which is directly implicated in rosetting. We demonstrate that NTS-DBL1α(1)-VarO binds to RBC and that heparin inhibits this interaction in a dose-dependent manner, thus mimicking heparin-mediated rosette disruption. We have determined the crystal structure of NTS-DBL1α(1), showing that NTS, previously thought to be a structurally independent component of PfEMP1, forms an integral part of the DBL1α domain. Using mutagenesis and docking studies, we have located the heparin-binding site, which includes NTS. NTS, unique to the DBL α-class domain, is thus an intrinsic structural and functional component of the N-terminal VarO domain. The specific interaction observed with heparin opens the way for developing antirosetting therapeutic strategies.
authors.affiliation: Institut Pasteur, Unité d'Immunologie Structurale, 75015 Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Juillerat
authors.forename: Anita
authors.initials: A
authors.lastname: Lewit-Bentley
authors.forename: Micheline
authors.initials: M
authors.lastname: Guillotte
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gangnard
authors.forename: Audrey
authors.initials: A
authors.lastname: Hessel
authors.forename: Bruno
authors.initials: B
authors.lastname: Baron
authors.forename: Inès
authors.initials: I
authors.lastname: Vigan-Womas
authors.forename: Patrick
authors.initials: P
authors.lastname: England
authors.forename: Odile
authors.initials: O
authors.lastname: Mercereau-Puijalon
authors.forename: Graham A
authors.initials: GA
authors.lastname: Bentley
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004912:Erythrocytes / Q000469:parasitology*; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010963:Plasmodium falciparum / Q000378:metabolism* / Q000472:pathogenicity; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012397:Rosette Formation
chemical_list: D015800:Protozoan Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum; D006493:Heparin