3zh2 | pdb_00003zh2

Structure of Plasmodium falciparum lactate dehydrogenase in complex with a DNA aptamer

spinqualitylabelsall models 3zh2, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3zh2 is a 6 chain structure with sequence from Plaf7. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Activity: L-lactate dehydrogenase, with EC number 1.1.1.27 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed DNA aptamers have significant potential as diagnostic and therapeutic agents, but the paucity of DNA aptamer-target structures limits understanding of their molecular binding mechanisms. Here, we report a distorted hairpin structure of a DNA aptamer in complex with an important diagnostic target for malaria: Plasmodium falciparum lactate dehydrogenase (PfLDH). Aptamers selected from a DNA library were highly specific and discriminatory for Plasmodium as opposed to human lactate dehydrogenase because of a counterselection strategy used during selection. Isothermal titration calorimetry revealed aptamer binding to PfLDH with a dissociation constant of 42 nM and 2:1 protein:aptamer molar stoichiometry. Dissociation constants derived from electrophoretic mobility shift assays and surface plasmon resonance experiments were consistent. The aptamer:protein complex crystal structure was solved at 2.1-A resolution, revealing two aptamers bind per PfLDH tetramer. The aptamers showed a unique distorted hairpin structure in complex with PfLDH, displaying a Watson-Crick base-paired stem together with two distinct loops each with one base flipped out by specific interactions with PfLDH. Aptamer binding specificity is dictated by extensive interactions of one of the aptamer loops with a PfLDH loop that is absent in human lactate dehydrogenase. We conjugated the aptamer to gold nanoparticles and demonstrated specificity of colorimetric detection of PfLDH over human lactate dehydrogenase. This unique distorted hairpin aptamer complex provides a perspective on aptamer-mediated molecular recognition and may guide rational design of better aptamers for malaria diagnostics. Structural basis for discriminatory recognition of Plasmodium lactate dehydrogenase by a DNA aptamer.,Cheung YW, Kwok J, Law AW, Watt RM, Kotaka M, Tanner JA Proc Natl Acad Sci U S A. 2013 Sep 16. PMID:24043813 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Lactate dehydrogenase 3D structures

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