title: Aldolase provides an unusual binding site for thrombospondin-related anonymous protein in the invasion machinery of the malaria parasite.
abstract: An actomyosin motor located underneath the plasma membrane drives motility and host-cell invasion of apicomplexan parasites such as Plasmodium falciparum and Plasmodium vivax, the causative agents of malaria. Aldolase connects the motor actin filaments to transmembrane adhesive proteins of the thrombospondin-related anonymous protein (TRAP) family and transduces the motor force across the parasite surface. The TRAP-aldolase interaction is a distinctive and critical trait of host hepatocyte invasion by Plasmodium sporozoites, with a likely similar interaction crucial for erythrocyte invasion by merozoites. Here, we describe 2.4-A and 2.7-A structures of P. falciparum aldolase (PfAldo) obtained from crystals grown in the presence of the C-terminal hexapeptide of TRAP from Plasmodium berghei. The indole ring of the critical penultimate Trp-residue of TRAP fits snugly into a newly formed hydrophobic pocket, which is exclusively delimited by hydrophilic residues: two arginines, one glutamate, and one glutamine. Comparison with the unliganded PfAldo structure shows that the two arginines adopt new side-chain rotamers, whereas a 25-residue subdomain, forming a helix-loop-helix unit, shifts upon binding the TRAP-tail. The structural data are in agreement with decreased TRAP binding after mutagenesis of PfAldo residues in and near the induced TRAP-binding pocket. Remarkably, the TRAP- and actin-binding sites of PfAldo seem to overlap, suggesting that both the plasticity of the aldolase active-site region and the multimeric nature of the enzyme are crucial for its intriguing nonenzymatic function in the invasion machinery of the malaria parasite.
authors.affiliation: Department of Biochemistry and Structural Genomics of Pathogenic Protozoa (SGPP) Consortium, University of Washington, Seattle, WA 98195, USA.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bosch
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Buscaglia
authors.forename: Brian
authors.initials: B
authors.lastname: Krumm
authors.forename: Bjarni P
authors.initials: BP
authors.lastname: Ingason
authors.forename: Robert
authors.initials: R
authors.lastname: Lucas
authors.forename: Claudia
authors.initials: C
authors.lastname: Roach
authors.forename: Timothy
authors.initials: T
authors.lastname: Cardozo
authors.forename: Victor
authors.initials: V
authors.lastname: Nussenzweig
authors.forename: Wim G J
authors.initials: WG
authors.lastname: Hol
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry* / Q000378:metabolism*; D007211:Indoles / Q000737:chemistry; D016778:Malaria, Falciparum / Q000469:parasitology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000472:pathogenicity*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D007211:Indoles; D015800:Protozoan Proteins; C069428:thrombospondin-related adhesive protein, protozoan; C030374:indole; D005634:Fructose-Bisphosphate Aldolase