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Ma J, Zhang J, Yan R. Recombinant Mammalian Prions: The “Correctly” Misfolded Prion Protein Conformers. Viruses 2022; 14:v14091940. [PMID: 36146746 PMCID: PMC9504972 DOI: 10.3390/v14091940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 08/22/2022] [Accepted: 08/27/2022] [Indexed: 11/17/2022] Open
Abstract
Generating a prion with exogenously produced recombinant prion protein is widely accepted as the ultimate proof of the prion hypothesis. Over the years, a plethora of misfolded recPrP conformers have been generated, but despite their seeding capability, many of them have failed to elicit a fatal neurodegenerative disorder in wild-type animals like a naturally occurring prion. The application of the protein misfolding cyclic amplification technique and the inclusion of non-protein cofactors in the reaction mixture have led to the generation of authentic recombinant prions that fully recapitulate the characteristics of native prions. Together, these studies reveal that recPrP can stably exist in a variety of misfolded conformations and when inoculated into wild-type animals, misfolded recPrP conformers cause a wide range of outcomes, from being completely innocuous to lethal. Since all these recPrP conformers possess seeding capabilities, these results clearly suggest that seeding activity alone is not equivalent to prion activity. Instead, authentic prions are those PrP conformers that are not only heritable (the ability to seed the conversion of normal PrP) but also pathogenic (the ability to cause fatal neurodegeneration). The knowledge gained from the studies of the recombinant prion is important for us to understand the pathogenesis of prion disease and the roles of misfolded proteins in other neurodegenerative disorders.
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Pasiana AD, Miyata H, Chida J, Hara H, Imamura M, Atarashi R, Sakaguchi S. Central Residues in Prion Protein PrP C Are Crucial for Its Conversion into the Pathogenic Isoform. J Biol Chem 2022; 298:102381. [PMID: 35973512 PMCID: PMC9478402 DOI: 10.1016/j.jbc.2022.102381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/05/2022] Open
Abstract
Conformational conversion of the cellular prion protein, PrPC, into the amyloidogenic isoform, PrPSc, is a key pathogenic event in prion diseases. However, the conversion mechanism remains to be elucidated. Here, we generated Tg(PrPΔ91-106)-8545/Prnp0/0 mice, which overexpress mouse PrP lacking residues 91-106. We showed that none of the mice became sick after intracerebral inoculation with RML, 22L, and FK-1 prion strains nor accumulated PrPScΔ91-106 in their brains except for a small amount of PrPScΔ91-106 detected in one 22L-inoculated mouse. However, they developed disease around 85 days after inoculation with bovine spongiform encephalopathy (BSE) prions with PrPScΔ91-106 in their brains. These results suggest that residues 91-106 are important for PrPC conversion into PrPSc in infection with RML, 22L, and FK-1 prions but not BSE prions. We then narrowed down the residues 91-106 by transducing various PrP deletional mutants into RML- and 22L-infected cells and identified that PrP mutants lacking residues 97-99 failed to convert into PrPSc in these cells. Our in vitro conversion assay also showed that RML, 22L, and FK-1 prions did not convert PrPΔ97-99 into PrPScΔ97-99, but BSE prions did. We further found that PrP mutants with proline residues at positions 97 to 99 or charged residues at positions 97 and 99 completely or almost completely lost their converting activity into PrPSc in RML- and 22L-infected cells. These results suggest that the structurally flexible and noncharged residues 97-99 could be important for PrPC conversion into PrPSc following infection with RML, 22L, and FK-1 prions but not BSE prions.
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Affiliation(s)
- Agriani Dini Pasiana
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Yahatanishi, Kitakyushu, Japan
| | - Junji Chida
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
| | - Hideyuki Hara
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
| | - Morikazu Imamura
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Ryuichiro Atarashi
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan.
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Imamura M, Tabeta N, Iwamaru Y, Takatsuki H, Mori T, Atarashi R. Spontaneous generation of distinct prion variants with recombinant prion protein from a baculovirus-insect cell expression system. Biochem Biophys Res Commun 2022; 613:67-72. [DOI: 10.1016/j.bbrc.2022.04.137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 04/29/2022] [Indexed: 11/25/2022]
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Imamura M, Mori T, Takatsuki H, Iwamaru Y, Atarashi R. [Elucidation of the Molecular Basis of Abnormal Prion Protein (PrP) Formation in a Cell-Free System Using Baculovirus and Insect Cell-derived Recombinant PrP]. YAKUGAKU ZASSHI 2019; 139:989-992. [PMID: 31257257 DOI: 10.1248/yakushi.18-00165-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The molecular basis underlying the conversion of normal prion protein (PrPC) into abnormal prion protein (PrPSc) has not been fully elucidated. The protein-misfolding cyclic amplification (PMCA) technique, which can amplify PrPSc in vitro with the use of intermittent sonication, mimics the process of in vivo PrPSc replication. Accumulating evidence suggests that co-factors other than PrP may play a crucial role in the faithful replication of PrPSc. In conventional PMCA, brain homogenates (BHs) from normal animals are used as the PrPC substrate. Since BHs contain many impurities, it is difficult to identify the co-factors using conventional PMCA. Thus, we developed a modified PMCA system using baculovirus and insect cell-derived recombinant PrP as a substrate (insect cell PMCA; iPMCA). We demonstrated that nucleic acids and glycosaminoglycans (GAGs) such as heparan sulfate (HS) or its analogue heparin (HP) are critical for PrPSc amplification in iPMCA. Of note, the addition of HS or HP restored the conversion efficiency in iPMCA under nucleic acid-depleted conditions. Moreover, the iPMCA products were infectious and preserved the strain properties of the input seed PrPSc. These data suggest that not only nucleic acids but also some GAGs play an important role in facilitating faithful replication of prions, at least in vitro.
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Affiliation(s)
- Morikazu Imamura
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki
| | - Tsuyoshi Mori
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki
| | - Hanae Takatsuki
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki
| | - Yoshifumi Iwamaru
- National Institute of Animal Health, National Agriculture and Food Research Organization (NARO)
| | - Ryuichiro Atarashi
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki
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Taguchi Y, Nishida N. Secondary-structure prediction revisited: Theoretical β-sheet propensity and coil propensity represent structures of amyloids and aid in elucidating phenomena involved in interspecies transmission of prions. PLoS One 2017; 12:e0171974. [PMID: 28199368 PMCID: PMC5310760 DOI: 10.1371/journal.pone.0171974] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 01/27/2017] [Indexed: 01/18/2023] Open
Abstract
Prions are unique infectious agents, consisting solely of abnormally-folded prion protein (PrPSc). However, they possess virus-like features, including strain diversity, the ability to adapt to new hosts and to be altered evolutionarily. Because prions lack genetic material (DNA and RNA), these biological phenomena have been attributed to the structural properties of PrPSc. Therefore, many structural models of the structure of PrPSc have been proposed based on the limited structural information available, regardless of the incompatibility with high-resolution structural analysis. Recently hypothesized models consist solely of β-sheets and intervening loops/kinks; i.e. parallel in-register β-sheet and β-solenoid models. Owing to the relative simplicity of these structural models of PrPSc, we hypothesized that numerical conversion of the primary structures with a relevant algorithm would enable quantitative comparison between PrPs of distinct primary structures. We therefore used the theoretical values of β-sheet (Pβ) and random-coil (Pc) propensity calculated by secondary structure prediction with a neural network, to analyze interspecies transmission of prions. By reviewing experiments in the literature, we ascertained the biological relevance of Pβ and Pc and found that these classical parameters surprisingly carry substantial information of amyloid structures. We also demonstrated how these parameters could aid in interpreting and explaining phenomena in interspecies transmissions. Our approach can lead to the development of a versatile tool for investigating not only prions but also other amyloids.
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Affiliation(s)
- Yuzuru Taguchi
- Division of Cellular and Molecular Biology, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JAPAN
- * E-mail:
| | - Noriyuki Nishida
- Division of Cellular and Molecular Biology, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, JAPAN
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Imamura M, Tabeta N, Kato N, Matsuura Y, Iwamaru Y, Yokoyama T, Murayama Y. Heparan Sulfate and Heparin Promote Faithful Prion Replication in Vitro by Binding to Normal and Abnormal Prion Proteins in Protein Misfolding Cyclic Amplification. J Biol Chem 2016; 291:26478-26486. [PMID: 27821590 DOI: 10.1074/jbc.m116.745851] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/26/2016] [Indexed: 11/06/2022] Open
Abstract
The precise mechanism underlying the conversion of normal prion protein (PrPC) into abnormal prion protein (PrPSc) remains unclear. Protein misfolding cyclic amplification (PMCA), an in vitro technique used for amplifying PrPSc, results in PrPSc replication that preserves the strain-specific characteristics of the input PrPSc; thus, PMCA mimics the process of in vivo PrPSc replication. Previous work has demonstrated that in PMCA, nucleic acids are critical for PrPSc amplification, but little information has been reported on glycosaminoglycan (GAG) participation in PrPSc replication in vitro Here, we investigated whether GAGs play a role in the faithful replication of PrPSc by using a modified PMCA performed with baculovirus-derived recombinant PrP (Bac-PrP) as a substrate. The addition of heparan sulfate (HS) or its analog heparin (HP) restored the conversion efficiency in PMCA that was inhibited through nucleic acid depletion. Moreover, the PMCA products obtained under these conditions were infectious and preserved the properties of the input PrPSc These data suggest that HS and HP play the same role as nucleic acids in facilitating faithful replication of prions in PMCA. Furthermore, we showed that HP binds to both Bac-PrP and Bac-PrPSc through the sulfated groups present on HP and that the N-terminal domain of Bac-PrPSc might potentially not be involved in the binding to HP. These results suggest that the interaction of GAGs such as HS and HP with PrPC and/or PrPSc through their sulfate groups is critical for the faithful replication of prions.
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Affiliation(s)
- Morikazu Imamura
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Naoko Tabeta
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Nobuko Kato
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Yuichi Matsuura
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Yoshifumi Iwamaru
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Takashi Yokoyama
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
| | - Yuichi Murayama
- From the National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-0856, Japan
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Imamura M, Kato N, Iwamaru Y, Mohri S, Yokoyama T, Murayama Y. Multiple affinity purification of a baculovirus-derived recombinant prion protein with in vitro ability to convert to its pathogenic form. Prep Biochem Biotechnol 2016; 47:1-7. [PMID: 26918377 DOI: 10.1080/10826068.2016.1155058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
We previously showed that baculovirus-derived recombinant prion protein (Bac-PrP) can be converted to the misfolded infectious form (PrPSc) by protein misfolding cyclic amplification, an in vitro conversion technique. Bac-PrP, with post-translational modifications, would be useful for various applications such as using PrP as an immunogen for generating anti-PrP antibody, developing anti-prion drugs or diagnostic assays using in vitro conversion systems, and establishing an in vitro prion propagation model. For this purpose, highly purified Bac-PrP with in vitro conversion activity is necessary for use as a PrPC source, to minimize contamination. Furthermore, an exogenous affinity tag-free form is desirable to avoid potential steric interference by the affinity tags during the conversion process. In this study, we established purification methods for the untagged Bac-PrP under native conditions by combining exogenous double-affinity tags, namely, a polyhistidine-tag and a profinity eXact tag, with an octarepeat sequence of the N-terminal region of PrP, which has metal ion-binding affinity. The untagged Bac-PrP with near-homogeneity was obtained by three-step affinity purification, and it was shown that the final, purified Bac-PrP could convert to its pathogenic form. The presented purification procedure could be applied not only to PrP but also to other eukaryotic, recombinant proteins that require high purity and intact physiological activity.
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Affiliation(s)
- Morikazu Imamura
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Nobuko Kato
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Yoshifumi Iwamaru
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Shirou Mohri
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Takashi Yokoyama
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
| | - Yuichi Murayama
- a Influenza and Prion Disease Research Center, National Institute of Animal Health , Tsukuba , Ibaraki , Japan
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Conformational properties of prion strains can be transmitted to recombinant prion protein fibrils in real-time quaking-induced conversion. J Virol 2014; 88:11791-801. [PMID: 25078700 DOI: 10.1128/jvi.00585-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phenomenon of prion strains with distinct biological characteristics has been hypothesized to be involved in the structural diversity of abnormal prion protein (PrP(Sc)). However, the molecular basis of the transmission of strain properties remains poorly understood. Real-time quaking-induced conversion (RT-QUIC) is a cell-free system that uses Escherichia coli-derived recombinant PrP (rPrP) for the sensitive detection of PrP(Sc). To investigate whether the properties of various prion strains can be transmitted to amyloid fibrils consisting of rPrP (rPrP fibrils) using RT-QUIC, we examined the secondary structure, conformational stability, and infectivity of rPrP fibrils seeded with PrP(Sc) derived from either the Chandler or the 22L strain. In the first round of the reaction, there were differences in the secondary structures, especially in bands attributed to β-sheets, as determined by infrared spectroscopy, and conformational stability between Chandler-seeded (1st-rPrP-fib(Ch)) and 22L-seeded (1st-rPrP-fib(22L)) rPrP fibrils. Of note, specific identifying characteristics of the two rPrP fibril types seen in the β-sheets resembled those of the original PrP(Sc). Furthermore, the conformational stability of 1st-rPrP-fib(Ch) was significantly higher than that of 1st-rPrP-fib(22L), as with Chandler and 22L PrP(Sc). The survival periods of mice inoculated with 1st-rPrP-fib(Ch) or 1st-rPrP-fib(22L) were significantly shorter than those of mice inoculated with mixtures from the mock 1st-round RT-QUIC procedure. In contrast, these biochemical characteristics were no longer evident in subsequent rounds, suggesting that nonspecific uninfected rPrP fibrils became predominant probably because of their high growth rate. Together, these findings show that at least some strain-specific conformational properties can be transmitted to rPrP fibrils and unknown cofactors or environmental conditions may be required for further conservation. Importance: The phenomenon of prion strains with distinct biological characteristics is assumed to result from the conformational variations in the abnormal prion protein (PrP(Sc)). However, important questions remain about the mechanistic relationship between the conformational differences and the strain diversity, including how strain-specific conformations are transmitted. In this study, we investigated whether the properties of diverse prion strains can be transmitted to amyloid fibrils consisting of E. coli-derived recombinant PrP (rPrP) generated by real-time quaking-induced conversion (RT-QUIC), a recently developed in vitro PrP(Sc) formation method. We demonstrate that at least some of the strain-specific conformational properties can be transmitted to rPrP fibrils in the first round of RT-QUIC by examining the secondary structure, conformational stability, and infectivity of rPrP fibrils seeded with PrP(Sc) derived from either the Chandler or the 22L prion strain. We believe that these findings will advance our understanding of the conformational basis underlying prion strain diversity.
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