4tpv

Crystal Structure of Hookworm Platelet Inhibitor

spinqualitylabelsall models 4tpv, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4tpv is a 2 chain structure with sequence from Ancylostoma caninum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.6Å Ligands: GOL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function HPI_ANCCA Hookworms inhibitor of platelet aggregation and adhesion (PubMed:10191228). Native protein inhibits platelet aggregation induced by ADP, epinephrine, and thrombin (PubMed:10191228). In addition, it prevents adhesion of resting platelets to immobilized fibrinogen and collagen (PubMed:10191228). May act by binding to glycoprotein IIb/IIIa (ITGA2B/ITGB3) and integrin alpha-2/beta-1 (ITGA1/ITGB1), respectively (PubMed:10191228). It is noteworthy that the recombinant protein fails to inhibit binding to fibrinogen (through ITGA2B/ITGB3) and collagen (through ITGA1/ITGB1) (PubMed:10191228, PubMed:26057788). Publication Abstract from PubMed Secreted protein components of hookworm species include a number of representatives of the cysteine-rich/antigen 5/pathogenesis-related 1 (CAP) protein family known as Ancylostoma-secreted proteins (ASPs). Some of these have been considered as candidate antigens for the development of vaccines against hookworms. The functions of most CAP superfamily members are poorly understood, but one form, the hookworm platelet inhibitor (HPI), has been isolated as a putative antagonist of the platelet integrins alphaIIbbeta3 and alpha2beta1. Here, the crystal structure of HPI is described and its structural features are examined in relation to its possible function. The HPI structure is similar to those of other ASPs and shows incomplete conservation of the sequence motifs CAP1 and CAP2 that are considered to be diagnostic of CAP superfamily members. The asymmetric unit of the HPI crystal contains a dimer with an extensive interaction interface, but chromatographic measurements indicate that it is primarily monomeric in solution. In the dimeric structure, the putative active-site cleft areas from both monomers are united into a single negatively charged depression. A potential Lys-Gly-Asp disintegrin-like motif was identified in the sequence of HPI, but is not positioned at the apex of a tight turn, making it unlikely that it interacts with the integrin. Recombinant HPI produced in Escherichia coli was found not to inhibit the adhesion of human platelets to collagen or fibrinogen, despite having a native structure as shown by X-ray diffraction. This result corroborates previous analyses of recombinant HPI and suggests that it might require post-translational modification or have a different biological function. The structure of hookworm platelet inhibitor (HPI), a CAP superfamily member from Ancylostoma caninum.,Ma D, Francischetti IM, Ribeiro JM, Andersen JF Acta Crystallogr F Struct Biol Commun. 2015 Jun 1;71(Pt 6):643-9. doi:, 10.1107/S2053230X1500271X. Epub 2015 May 20. PMID:26057788 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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