Conformational Conversion Research Articles

The Lys 280 → Gln mutation mimicking disease-linked acetylation of Lys 280 in tau extends the structural core of fibrils and modulates their catalytic properties.

Amyloid fibrillar aggregates isolated from the brains of patients with neurodegenerative diseases invariably have post-translational modifications (PTMs). The roles that PTMs play in modulating the structures and polymorphism of amyloid aggregates, and hence their ability to catalyze the conversion of monomeric protein to their fibrillar structure is, however, poorly understood. This is particularly true in the case of tau aggregates, where specific folds of fibrillar tau have been implicated in specific tauopathies. Several PTMs, including acetylation at Lys 280, increase aggregation of tau in the brain, and increase neurodegeneration. In this study, tau-K18 K280Q, in which the Lys 280 → Gln mutation is used to mimic acetylation at Lys 280, is shown, using HX-MS measurements, to form fibrils with a structural core that is longer than that of tau-K18 fibrils. Measurements of critical concentrations show that the binding affinity of monomeric tau-K18 for its fibrillar counterpart is only marginally more than that of monomeric tau-K18 K280Q for its fibrillar counterpart. Quantitative analysis of the kinetics of seeded aggregation, using a simple Michaelis-Menten-like model, in which the monomer first binds and then undergoes conformational conversion to β-strand, shows that the fibrils of tau-K18 K280Q convert monomeric protein more slowly than do fibrils of tau-K18. In contrast, monomeric tau-K18 K280Q is converted faster to fibrils than is monomeric tau-K18. Thus, the effect of Lys 280 acetylation on tau aggregate propagation in brain cells is expected to depend on the amount of acetylated tau present, and on whether the propagating seed is acetylated at Lys 280 or not.

Neurometals in the Pathogenesis of Prion Diseases.

Prion diseases are progressive and transmissive neurodegenerative diseases. The conformational conversion of normal cellular prion protein (PrPC) into abnormal pathogenic prion protein (PrPSc) is critical for its infection and pathogenesis. PrPC possesses the ability to bind to various neurometals, including copper, zinc, iron, and manganese. Moreover, increasing evidence suggests that PrPC plays essential roles in the maintenance of homeostasis of these neurometals in the synapse. In addition, trace metals are critical determinants of the conformational change and toxicity of PrPC. Here, we review our studies and other new findings that inform the current understanding of the links between trace elements and physiological functions of PrPC and the neurotoxicity of PrPSc.

Integrative identification of human serpin PAI-1 inhibitors from Dracaena dragon blood and molecular implications for inhibitor-induced PAI-1 allosterism.

Human plasminogen activator inhibitor-1 (PAI-1) is an important component of the coagulation system and has been recognized as a potential therapeutic target of diverse cardiovascular disorders. Previously, it was found that the extracts from the Chinese medicine Dracaena dragon blood have potent inhibitory activity against PAI-1, but it is unclear which constituents directly participate in the inhibition and how do they regulate PAI-1 at molecular level. Here, we describe an integrated strategy to identify the dragon blood's chemical constituents that can directly target PAI-1. With the strategy, five compounds 1-5 are hit as promising PAI-1 inhibitor candidates, from which three are measured to have high or moderate activity against PAI-1. In particular, the compound 3 is determined to exhibit the highest potency; this value is roughly comparable with the widely used PAI-1 inhibitor Tiplaxtinin. We further examine the molecular effect of compound 3 on PAI-1 conformation at structural level. It is supposed that small-molecule inhibitor regulates the reactive center loop (RCL) of PAI-1 through an allosterism, that is, binding of compound 3 to PAI-1 can allosterically stabilize RCL in latent form, thus promoting PAI-1 conformational conversion from metastable active form to the inactive latent form. Long-term atomistic simulations also demonstrate that removal of compound 3 can destabilize the structured β-stranded conformation of RCL in latent form, although the current simulations are still not sufficient to characterize the full conversion dynamics trajectory.

Short and sweet: How glycans impact prion conversion, cofactor interactions, and cross-species transmission.

Prion diseases are transmissible and incurable neurodegenerative disorders of humans and animals. Similar to other neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease, prion diseases are characterized by protein aggregation in the central nervous system (CNS). The key molecular event in prion disease is the conformational conversion of the cellular prion protein, PrPC, into a misfolded and aggregated conformer, PrPSc, which templates further PrPC misfolding [1]. Although this same protein misfolding event occurs in all prion diseases, affected individuals expressing identical PrPC sequences can exhibit strikingly heterogeneous clinical and pathological phenotypes. These phenotypic differences have been linked to distinct PrPSc conformations, known as strains, yet the source of prion strain diversity is incompletely understood. One potential contributor to strain diversity lies in the posttranslational modifications (PTMs) on PrPC, which add a layer of structural complexity to an otherwise highly conserved protein. PrPC is posttranslationally modified by the covalent linkage of (i) 0 to 2 N-linked glycans at positions 181 and 197 (human PrP) and (ii) a glycosylphosphatidylinositol (GPI) moiety, which anchors PrPC in the outer leaflet of the plasma membrane [2,3]. The N-linked glycans on PrPC are branched [bi- (51%), tri- (32%), or tetra-antennary (17%)] and terminally sialylated, predominantly via alpha 2,6 linkages [4–6]. While necessary for regulating protein interactions and function, PTMs can profoundly modulate the pathogenesis of neurodegenerative diseases. For example, aberrant hyperphosphorylation of tau protein leads to tau detachment from microtubules and fibrillization into neurofibrillary tangles, a pathologic hallmark of Alzheimer’s disease. Prion diseases are no different, and the presence of PrP PTMs can markedly alter both the disease phenotype and transmission barrier. Here we explore how PrP PTMs impact prion conversion, cross-species transmission, the neuroinflammatory response, and PrP interaction with cofactors.

Hydrogen bonding interactions in the 1,1,1,3,3,3-hexafluoro-2-propanol∙∙∙1,4-dioxane complex: Rotational spectroscopy and density functional theory calculations

The rotational spectrum of the binary complex formed between 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and 1,4-dioxane was investigated using a chirped pulse Fourier transform microwave spectrometer. HFIP is known to be an exceptional solvent that catalyzes the epoxidation of olefins by hydrogen peroxide. The addition of 1,4-dioxane can severely reduce HFIP’s ability to boost the epoxidation rate, possibly through its intermolecular interactions with HFIP. It is therefore of considerable interest to examine the non-covalent interactions between HFIP and 1,4-dioxane in detail. Theoretical conformational searches were carried out for the binary HFIP···1,4-dioxane complex and 17 minimum energy structures were identified. Seven of them are within an energy window of 7 kJ mol−1, while the three lowest energy ones are within 1.4 kJ mol−1. Experimentally, only the rotational spectrum of the most stable conformer was detected and assigned. To understand the non-observation of the other low energy conformers in the supersonic jet expansion, subsequent analyses were performed to estimate the conformational conversion barriers. The detected conformer contains a trans HFIP subunit which is hydrogen-bonded to an O atom of 1,4-dioxane and is further stabilized by weak F···H attractive interactions. The intermolecular interactions in HFIP···1,4-dioxane were analyzed and visualized using QTAIM, NCI and SAPT approaches and the interaction energies compared to the HFIP dimer and related complexes of HFIP and 1,4-dioxane with water.

Hydrogen-bond-driven dimers of naphthyridine derivatives for selective identification of DNA G-quadruplexes.

G-quadruplex (GQ) ligands as potential anti-cancer drugs have received extensive attention. Large aromatic systems are usually considered in the design of the ligands to improve the binding with GQs, which are typically constructed by the combination of small modules with covalent bonds. In this study, we presented a non-covalent bond approach to construct GQ ligands with an extended planar structure. The ligands were stable dimers assembled through quadruplex intermolecular hydrogen bonds between two molecules of naphthyridine derivatives. Spectroscopic analyses showed that dimeric ligands could stabilize GQs with an increase of the melting temperature up to 12 °C and induced conformational conversion of hybrid GQs. Confocal fluorescence microscopy confirmed the enrichment of naphthyridine ligands in the nucleus. The ligands showed moderate cytotoxicity against HeLa cells with an IC50 value of 7.5 μg mL-1 and effectively induced growth inhibition and apoptosis in HeLa cells. These results confirmed the feasibility of the quick building of GQ ligands through intermolecular interactions of simple molecules that are easily obtained during synthesis, which is helpful for GQ ligand design and quick establishment of a ligand library through the self-assembly of easily available molecular components.

Amyloid Aggregation under the Lens of Liquid–Liquid Phase Separation

Increasing experiments suggest that amyloid peptides can undergo liquid-liquid phase separation (LLPS) before the formation of amyloid fibrils. However, the exact role of LLPS in amyloid aggregation at the molecular level remains elusive. Here, we investigated the LLPS and amyloid fibrillization of a coarse-grained peptide, capable of capturing fundamental properties of amyloid aggregation over a wide range of concentrations in molecular dynamics simulations. On the basis of the Flory-Huggins theory of polymer solutions, we determined the binodal and spinodal concentrations of LLPS in the low-concentration regime, ϕBL and ϕSL, respectively. Only at concentrations above ϕBL, peptides formed metastable or stable oligomers corresponding to the high-density liquid phase (HDLP) in LLPS, out of which the nucleated conformational conversion to fibril seeds occurred. Below ϕSL, the HDLP was metastable and transient, and the subsequent fibrillization process followed the traditional nucleation and elongation mechanisms. Only above ϕSL, the HDLP became stable, and the initial fibril nucleation and growth were governed by the high local peptide concentrations. The predicted saturation of amyloid aggregation half-times with increasing peptide concentration to a constant, instead of the traditional power-law scaling to zero, was confirmed by simulations and by a thioflavin-T kinetic assay and the transmission electron microscopy of islet amyloid polypeptide (IAPP) aggregation. Our study provides a unified picture of amyloid aggregation for a wide range of concentrations within the framework of LLPS, which may help us better understand the etiology of amyloid diseases, where the amyloid protein concentration can vary by ∼9 orders of magnitude depending on the organ location and facilitate the engineering of novel amyloid-based functional materials.

Physicochemical, structural and gelation properties of arachin-basil seed gum composite gels: Effects of salt types and concentrations

In this study, the effects of calcium chloride (CaCl2) and sodium chloride (NaCl) with different concentrations (0–20 mM) on the properties of arachin and basil seed gum composite gels were investigated. The results showed that the G′, G″ and gel strength of the composite gels were enhanced by Ca2+ and Na+ at a low concentration and decreased at high concentrations. An appropriate concentration of Ca2+ or Na+ (10 mM) strengthened the electrostatic forces, hydrophobic interactions, hydrogen bonds, disulfide bonds and facilitated a conformation conversion of the secondary structures from α-helix to β-sheet. These changes were responsible for the improved hydration properties including water-holding capacity, freeze-thaw stability and swelling behavior of the composite gels in the presence of 10 mM Ca2+ or Na+, which could be explained by the images of compact and uniform microstructures. High concentration of salt ions (15–20 mM) hindered the formation of regular gel network. These findings may facilitate the design of arachin-based gel products with improved texture and sensory characteristics.

Tumor tissues diagnosis with PIEE lipid droplet vesicles

A molecule ANB (6-(4-aminostyryl)-1,3-dioxo-1H-benzo[de]isoquinolin -2(3 H)-yl)-n-butane), was developed for fluorescence turn-on imaging of cancer cells lipid droplets (LDs). ANB exercised synergistically aggregation induced emission enhancement and photochromism, which are essential to construct a photoinduced emission enhancement (PIEE) LDs. The fluorescent nanostructures PIEE-LDs extremely improve intracellular imaging contrast with high emission intensity, high emission contrast to cytosol and high photostability. Following these unique optical properties, we statistically analyzed the differences of LDs between cancer and normal cells as well as successfully observed LDs progression and fusion in living cells over a long period. Consequently, the xenograft tumor tissues were favorably distinguished from normal based on this superior PIEE-LDs. It is known that ANB exhibited excited-state conformational conversion between the twist intramolecular charge transfer (TICT) and local excited (LE) states. Based on the results of our studies, we found that LE state became dominate and presented aggregation induced emission enhancement when ANB stay in LDs, which allows us to build a fluorescent nanovesicle model to explain the distinct fluorescence imaging of ANB in LDs. Furthermore, photochromism occurred when irradiation that could promoted emission behavior of bright nanovesicles LDs to further level, and achieve PIEE-LDs.

Conformal Polarization Conversion Metasurface for Omni-Directional Circular Polarization Antenna Application

In this article, conformal linear-to-circular (LTC) polarization conversion metasurface (MS) in transmission mode is engineered and fabricated. The conformal MS is cylinder-shaped with curved elements bent on the cylinder wall. First, the anisotropic element with the capability of LTC polarization conversion in high transmission efficiency is designed and simulated, and the electromagnetic response on the variation of the curvature radius of the conformal element is discussed. Second, the cylinder conformal polarization conversion MS is engineered based on the anisotropic element. Then by launching a monopole antenna at the center of the cylindrical axis as the feed source, the omni-directional circular polarization antenna is implemented. More importantly, the height, radius, and element number along the longitudinal direction of the MS are optimized to obtain an optimized performance of the antenna. Finally, the antenna system is fabricated, assembled, and measured. The device can operate in 9.9–10.1 GHz with an axial ratio lower than 3 dB along the circumferential direction and at 10 GHz the radiation fluctuation along the circumference is less than 1 dB. This study opens up a new way to design conformal MS on a curved surface and affords an efficient alternative for circular polarization antenna design.

Binding of Cu2+ to Aβ1-29 causes aggregation and toxicity in SH-SY5Y cells

The accumulation and aggregation of amyloid-β (Aβ) are critical factors in the pathogenesis of Alzheimer’s disease (AD). Several studies have indicated that metal ions such as Cu2+and Zn2+ play a key role in the formation and stabilization of neurotoxic Aβ aggregates, however the molecular mechanisms underlying Aβ cytotoxicity have not yet been fully elucidated. Previously, we showed that the Aβ-derived fragment peptide (Aβ-FrP), Aβ1-19, altered conformation in the presence of Cu2+, inhibiting its digestion by metalloproteinase-7 (MMP-7). In this study we demonstrated that Aβ1-19 did not form aggregates in the presence of Cu2+. Therefore, we synthesized a new Aβ-FrP, Aβ1-29, which displayed Cu2+-dependent conformational conversion and aggregate formation. Aβ1-29 was cleaved by MMP-7, however this reaction was inhibited in the presence of Cu2+ in a similar way to Aβ1-19. Interestingly, Aβ1-29 showed conformational conversion and aggregate formation in the presence of Zn2+, however this did not confer resistance against MMP-7 cleavage. Moreover, Aβ1-29 induced the apoptotic cell death of neural SH-SY5Y cells in the presence of Cu2+ but not Zn2+. These results suggest that Cu2+, unlike Zn2+, may play an important role in the aggregation mechanism of Aβ and thus in the pathology of AD.

Molecular Interaction of Protein-Pigment C-Phycocyanin with Bovine Serum Albumin in a Gomphosis Structure Inhibiting Amyloid Formation.

Accumulation of amyloid fibrils in organisms accompanies many diseases. Natural extracts offer an alternative strategy to control the process with potentially fewer side effects. In this study, the inhibition of C-phycocyanin from Spirulina sp. on amyloid formation of bovine serum albumin (BSA) during a 21-day incubation was investigated using fluorescence and circular dichroism (CD), and mechanisms were explored via kinetic fitting and molecular docking. C-phycocyanin (0–50 µg/mL) hindered the amyloid formation process of BSA with increased half-lives (12.43–17.73 days) based on fluorescence intensity. A kinetic model was built and showed that the k1 decreased from 1.820 × 10−2 d−1 to 2.62 × 10−3 d−1 with the increase of C-phycocyanin, while k2 showed no changes, indicating that the inhibition of BSA fibrillation by C-phycocyanin occurred in a spontaneous process instead of self-catalyzed one. CD results show that C-phycocyanin inhibited conformational conversion (α-helices and β-sheets) of BSA from day 6 to day 18. Molecular docking suggested that C-phycocyanin may hinder BSA fibrillation by hydrogen-bonding > 6 of 27 α-helices of BSA in a gomphosis-like structure, but the unblocked BSA α-helices might follow the self-catalytic process subsequently.

Self-Assembly of Switchable Protein Nanocages via Allosteric Effect

Protein cages have promising applications in highly efficient gene transportation. Many methods of engineering protein–interface interactions have been developed to build such viral mimics. Missing...

Adsorption of nitrosamine conformers on the C24, B12N12, Be12O12 and Al12P12 nanocages and their conversion to nitrogen and water molecules: A DFT study

Structure optimizations for adsorption configurations of nitrosamine conformers on sodalite like cages of Carbon (CSL, C24), boron nitride (BNSL, B12N12), beryllium oxide (BeOSL, Be12O12), and aluminum phosphide (AlPSL, Al12P12) were carried out using the CAM‒B3LYP and wB97xd/6–31+G(d,p) methods. Energetics, enthalpies, and Gibbs free energies of adsorptions of nitrosamine conformers were obtained. Reaction mechanisms of nitrosamine conformer conversion to N2 and H2O on the CSL, BNSL, BeOSL, and AlPSL cages, and their energetic profiles were obtained. The nitrosamine conversion to N2 and H2O on the CSL cage, one reaction path of three steps, was found. Reaction mechanisms of nitrosamine conversion to N2 and H2O on the BNSL, BeOSL, and AlPSL cages have two reaction steps: adsorption and conversion steps, respectively. All the nanocages, CSL, BNSL, BeOSL, and AlPSL, can be used as catalysts in the conversion reaction of nitrosamine (toxic gas) to N2 and H2O (non‒toxic gases).

Strain-Dependent Prion Infection in Mice Expressing Prion Protein with Deletion of Central Residues 91-106.

Conformational conversion of the cellular prion protein, PrPC, into the abnormally folded isoform, PrPSc, is a key pathogenic event in prion diseases. However, the exact conversion mechanism remains largely unknown. Transgenic mice expressing PrP with a deletion of the central residues 91–106 were generated in the absence of endogenous PrPC, designated Tg(PrP∆91–106)/Prnp0/0 mice and intracerebrally inoculated with various prions. Tg(PrP∆91–106)/Prnp0/0 mice were resistant to RML, 22L and FK-1 prions, neither producing PrPSc∆91–106 or prions in the brain nor developing disease after inoculation. However, they remained marginally susceptible to bovine spongiform encephalopathy (BSE) prions, developing disease after elongated incubation times and accumulating PrPSc∆91–106 and prions in the brain after inoculation with BSE prions. Recombinant PrP∆91-104 converted into PrPSc∆91–104 after incubation with BSE-PrPSc-prions but not with RML- and 22L–PrPSc-prions, in a protein misfolding cyclic amplification assay. However, digitonin and heparin stimulated the conversion of PrP∆91–104 into PrPSc∆91–104 even after incubation with RML- and 22L-PrPSc-prions. These results suggest that residues 91–106 or 91–104 of PrPC are crucially involved in prion pathogenesis in a strain-dependent manner and may play a similar role to digitonin and heparin in the conversion of PrPC into PrPSc.

Prion protein signaling induces M2 macrophage polarization and protects from lethal influenza infection in mice.

The cellular prion protein, PrPC, is a glycosylphosphatidylinositol anchored-membrane glycoprotein expressed most abundantly in neuronal and to a lesser extent in non-neuronal cells. Its conformational conversion into the amyloidogenic isoform in neurons is a key pathogenic event in prion diseases, including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. However, the normal functions of PrPC remain largely unknown, particularly in non-neuronal cells. Here we show that stimulation of PrPC with anti-PrP monoclonal antibodies (mAbs) protected mice from lethal infection with influenza A viruses (IAVs), with abundant accumulation of anti-inflammatory M2 macrophages with activated Src family kinases (SFKs) in infected lungs. A SFK inhibitor dasatinib inhibited M2 macrophage accumulation in IAV-infected lungs after treatment with anti-PrP mAbs and abolished the anti-PrP mAb-induced protective activity against lethal influenza infection in mice. We also show that stimulation of PrPC with anti-PrP mAbs induced M2 polarization in peritoneal macrophages through SFK activation in vitro and in vivo. These results indicate that PrPC could activate SFK in macrophages and induce macrophage polarization to an anti-inflammatory M2 phenotype after stimulation with anti-PrP mAbs, thereby eliciting protective activity against lethal infection with IAVs in mice after treatment with anti-PrP mAbs. These results also highlight PrPC as a novel therapeutic target for IAV infection.

Integration of ion-tuned oligonucleotide structural motifs and DNA-templated copper nanoclusters as a manipulable logic device

Molecular logic gates possess great potential for multi-parameter sensing, intelligent diagnostics, and molecular computation. One remaining challenge was to construct novel new logic gates based on smart nanomaterials and functional nucleic acids. In this study, two novel new logic devices were constructed utilizing ion-tuned DNA/copper nanoclusters (CuNCs), which were dual-responsive to K+ and H+. By merely altering the arrangement of a specific sequence of the DNA stabilizer, two kinds of well-designed DNA probes permuted by G-tracts, C-tracts, and poly-T were designed as the building blocks of the logic device. Poly-T acted as the template for the formation of CuNCs. G-tracts and C-tracts enabled a K+/H+-responsive conformational switch into G-quadruplex (G4) and i-motif structures. Such a conformational conversion significantly modulated the fluorescence behaviors of CuNCs. This study discovered the unique interaction between the logic device and graphene oxide (GO). The logic devices were implemented for the analysis of K+ and microRNA.

Molecular basis for the inhibitory effects of 5-hydroxycyclopenicillone on the conformational transition of Aβ40 monomer

Previous studies have indicated that 5-hydroxycyclopenicillone (HCP), an active compound derived from marine sponge, could inhibit oligomerization of amyloid β-protein (Aβ). However, the molecular basis for the interaction between HCP and Aβ remains unclear. Herein, all-atom molecular dynamics (MD) simulations were used to explore the conformational conversion of an Aβ40 monomer at different concentrations (0-40 mM) of HCP at the atomic level. It is confirmed that the conformational transition of the Aβ40 monomer is prevented by HCP in a concentration-dependent manner in silico. In 40 mM HCP solution, the initial α-helix-rich conformation of Aβ40 monomer is kept under the action of HCP. The intra-peptide hydrophobic collapse and D23-K28 salt bridge are prevented by HCP. Moreover, it is indicated that the non-polar binding energy dominates the binding between HCP and Aβ40 monomer as evaluated by molecular mechanics Poisson-Boltzmann surface area method. And, the residues of F4, Y10, V12, L17 and L34 in Aβ40 might contribute to the binding energy in HCP-Aβ40 complex. All these results elucidate the molecular mechanism underlying the inhibitory effects of HCP against the conformational transformation of Aβ40, providing a support that HCP may be developed as a potential anti-Aβ compound for the treatment of Aβ-related diseases. Communicated by Ramaswamy H. Sarma

Protein-sol pKa: prediction of electrostatic frustration, with application to coronaviruses.

MotivationEvolution couples differences in ambient pH to biological function through protonatable groups, in particular, those that switch from buried to exposed and alter protonation state in doing so. We present a tool focusing on structure-based discovery and display of these groups.ResultsSince prediction of buried group pKas is computationally intensive, solvent accessibility of ionizable groups is displayed, from which the user can iteratively select pKa calculation centers. Results are color-coded, with emphasis on buried groups. Utility is demonstrated with benchmarking against known pH sensing sites in influenza virus hemagglutinin and in variants of murine hepatitis virus, a coronavirus. A pair of histidine residues, which are conserved in coronavirus spike proteins, are predicted to be electrostatically frustrated at acidic pH in both pre- and post-fusion conformations. We suggest that an intermediate expanded conformation at endosomal pH could relax the frustration, allowing histidine protonation and facilitating conformational conversion of coronavirus spike protein.Availability and implementationThis tool is available at http://www.protein-sol.manchester.ac.uk/pka/.

Incomplete glycosylation during prion infection unmasks a prion protein epitope that facilitates prion detection and strain discrimination

The causative factors underlying conformational conversion of cellular prion protein (PrPC) into its infectious counterpart (PrPSc) during prion infection remain undetermined, in part because of a lack of monoclonal antibodies (mAbs) that can distinguish these conformational isoforms. Here we show that the anti-PrP mAb PRC7 recognizes an epitope that is shielded from detection when glycans are attached to Asn-196. We observed that whereas PrPC is predisposed to full glycosylation and is therefore refractory to PRC7 detection, prion infection leads to diminished PrPSc glycosylation at Asn-196, resulting in an unshielded PRC7 epitope that is amenable to mAb recognition upon renaturation. Detection of PRC7-reactive PrPSc in experimental and natural infections with various mouse-adapted scrapie strains and with prions causing deer and elk chronic wasting disease and transmissible mink encephalopathy uncovered that incomplete PrPSc glycosylation is a consistent feature of prion pathogenesis. We also show that interrogating the conformational properties of the PRC7 epitope affords a direct means of distinguishing different prion strains. Because the specificity of our approach for prion detection and strain discrimination relies on the extent to which N-linked glycosylation shields or unshields PrP epitopes from antibody recognition, it dispenses with the requirement for additional standard manipulations to distinguish PrPSc from PrPC, including evaluation of protease resistance. Our findings not only highlight an innovative and facile strategy for prion detection and strain differentiation, but are also consistent with a mechanism of prion replication in which structural instability of incompletely glycosylated PrP contributes to the conformational conversion of PrPC to PrPSc.