51
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Bentley AA, Merkulov SM, Peng Y, Rozmarynowycz R, Qi X, Pusztai-Carey M, Merrick WC, Yee VC, McCrae KR, Komar AA. Chimeric glutathione S-transferases containing inserts of kininogen peptides: potential novel protein therapeutics. J Biol Chem 2012; 287:22142-50. [PMID: 22577144 DOI: 10.1074/jbc.m112.372854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The study of synthetic peptides corresponding to discrete regions of proteins has facilitated the understanding of protein structure-activity relationships. Short peptides can also be used as powerful therapeutic agents. However, in many instances, small peptides are prone to rapid degradation or aggregation and may lack the conformation required to mimic the functional motifs of the protein. For peptides to function as pharmacologically active agents, efficient production or expression, high solubility, and retention of biological activity through purification and storage steps are required. We report here the design, expression, and functional analysis of eight engineered GST proteins (denoted GSHKTs) in which peptides ranging in size from 8 to 16 amino acids and derived from human high molecular weight kininogen (HK) domain 5 were inserted into GST (between Gly-49 and Leu-50). Peptides derived from HK are known to inhibit cell proliferation, angiogenesis, and tumor metastasis, and the biological activity of the HK peptides was dramatically (>50-fold) enhanced following insertion into GST. GSHKTs are soluble and easily purified from Escherichia coli by affinity chromatography. Functionally, these hybrid proteins cause inhibition of endothelial cell proliferation. Crystallographic analysis of GSHKT10 and GSHKT13 (harboring 10- and 13-residue HK peptides, respectively) showed that the overall GST structure was not perturbed. These results suggest that the therapeutic efficacy of short peptides can be enhanced by insertion into larger proteins that are easily expressed and purified and that GST may potentially be used as such a carrier.
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Affiliation(s)
- Amber A Bentley
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115, USA
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52
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Rastogi N, Mitra K, Kumar D, Roy R. Metal Ions as Cofactors for Aggregation of Therapeutic Peptide Salmon Calcitonin. Inorg Chem 2012; 51:5642-50. [DOI: 10.1021/ic202604v] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Neeraj Rastogi
- Centre of Biomedical Magnetic
Resonance, Sanjay Gandhi Postgraduate Institute of Medical Sciences
Campus, Lucknow 226014, India
| | - Kalyan Mitra
- E. M. Unit, Central Drug Research
Institute, CSIR, Lucknow 226001, India
| | - Dinesh Kumar
- Centre of Biomedical Magnetic
Resonance, Sanjay Gandhi Postgraduate Institute of Medical Sciences
Campus, Lucknow 226014, India
| | - Raja Roy
- Centre of Biomedical Magnetic
Resonance, Sanjay Gandhi Postgraduate Institute of Medical Sciences
Campus, Lucknow 226014, India
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53
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Huang R, Vivekanandan S, Brender JR, Abe Y, Naito A, Ramamoorthy A. NMR characterization of monomeric and oligomeric conformations of human calcitonin and its interaction with EGCG. J Mol Biol 2011; 416:108-20. [PMID: 22200484 DOI: 10.1016/j.jmb.2011.12.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 12/05/2011] [Accepted: 12/10/2011] [Indexed: 11/17/2022]
Abstract
Calcitonin is a 32-residue peptide hormone known for its hypocalcemic effect and its inhibition of bone resorption. While calcitonin has been used in therapy for osteoporosis and Paget's disease for decades, human calcitonin (hCT) forms fibrils in aqueous solution that limit its therapeutic application. The molecular mechanism of fiber formation by calcitonin is not well understood. Here, high-resolution structures of hCT at concentrations of 0.3 mM and 1 mM have been investigated using NMR spectroscopy. Comparing the structures of hCT at different concentrations, we discovered that the peptide undergoes a conformational transition from an extended to a β-hairpin structure in the process of molecular association. This conformational transition locates the aromatic side chains of Tyr12 and Phe16 in a favorable way for intermolecular π-π stacking, which is proposed to be a crucial interaction for peptide association and fibrillation. One-dimensional (1)H NMR experiments confirm that oligomerization of hCT accompanies the conformational transition at 1 mM concentration. The effect of the polyphenol epigallocatechin 3-gallate (EGCG) on hCT fibrillation was also investigated by NMR and electron microscopy, which show that EGCG efficiently inhibits fibril formation of hCT by preventing the initial association of hCT before fiber formation. The NMR experiments also indicate that the interaction between aromatic rings of EGCG and the aromatic side chains of the peptide may play an important role in inhibiting fibril formation of hCT.
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Affiliation(s)
- Rui Huang
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
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54
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Kratzsch J, Petzold A, Raue F, Reinhardt W, Bröcker-Preuβ M, Görges R, Mann K, Karges W, Morgenthaler N, Luster M, Reiners C, Thiery J, Dralle H, Fuhrer D. Basal and Stimulated Calcitonin and Procalcitonin by Various Assays in Patients with and without Medullary Thyroid Cancer. Clin Chem 2011; 57:467-74. [DOI: 10.1373/clinchem.2010.151688] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND
Calcitonin (CT) is a sensitive marker for evaluation of medullary thyroid cancer (MTC). However, CT measurement can vary with assay- and nonassay-dependent factors, and procalcitonin (PCT) measurement has been proposed for evaluating questionable increases in CT.
METHODS
We tested 2 fully automated CT assays (Immulite [IL] and Liaison [LIA]) and 1 nonautomated CT assay (IRMA, Medipan) and compared these results with PCT (Brahms Kryptor). We evaluated preanalytical conditions and PCT cross-reactivity in sera of 437 patients with clinical conditions associated with hypercalcitoninemia. Additionally, we determined the true “nil” CT concentration in 60 thyroidectomized patients and defined CT cutoff concentrations for pentagastrin stimulation testing in 13 chronic kidney disease (CKD) patients and 10 MTC patients.
RESULTS
Markedly decreased CT concentrations were found after storage of sera for >2 h at room temperature and >6 h at 4 °C. Cutoff concentrations for basal and stimulated CT were disease and assay dependent. Proton pump inhibitor therapy was the most frequent reason for increased CT. PCT concentrations were higher in patients with MTC than in patients with CKD without infections (P < 0.001). Whereas IL and LIA demonstrated comparable analytical quality, the IRMA gave increased CT concentrations in nil sera and showed cross-reactivity with PCT in patients with concomitant bacterial infection.
CONCLUSIONS
IL, LIA, and IRMA detected increased CT concentrations in non-MTC patients and discriminated MTC from CKD patients in pentagastrin tests. PCT assessment may be helpful in the diagnostic work-up of increased CT concentrations in questionable clinical circumstances.
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Affiliation(s)
- Jürgen Kratzsch
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics; and
| | - Anne Petzold
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics; and
- Department of Internal Medicine, Neurology and Dermatology, Clinic for Endocrinology and Nephrology, University of Leipzig, Leipzig, Germany
| | | | | | | | - Rainer Görges
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany
| | | | - Wolfram Karges
- Department of Internal Medicine III, RWTH Aachen University, Aachen, Germany
| | - Nils Morgenthaler
- Department of Research, Brahms Aktiengesellschaft, Henningsdorf, Germany
| | - Markus Luster
- Department of Nuclear Medicine, University of Ulm, Ulm, Germany
| | - Christoph Reiners
- Department of Nuclear Medicine, University of Würzburg, Würzburg, Germany
| | - Joachim Thiery
- Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics; and
| | - Henning Dralle
- Department of General, Visceral and Vascular Surgery, University Halle-Wittenberg, Halle, Germany
| | - Dagmar Fuhrer
- Department of Internal Medicine, Neurology and Dermatology, Clinic for Endocrinology and Nephrology, University of Leipzig, Leipzig, Germany
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55
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Rational development of a strategy for modifying the aggregatibility of proteins. Proc Natl Acad Sci U S A 2011; 108:4297-302. [PMID: 21368182 DOI: 10.1073/pnas.1100195108] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The conversion of peptide and proteins from their soluble state into well-organized aggregates, together with the accompanied oxidation of methionine residue, presents a significant challenge to human health, to the manufacture of protein therapeutics, and to the synthesis of proteins and glycoproteins. Despite their fundamental importance, little is known about the molecular basis of these two side reactions and their control. Here, using chemical peptide synthesis, we further confirmed the importance of the balance between hydrophobic interactions and electrostatic repulsive forces in inducing and inhibiting aggregation and methionine oxidation. Most importantly, through extending the established principle, we are able to effectively stabilize the problematic peptide fragment through the attachment of cleavable arginine tags. Future applications of our approach are expected to facilitate the synthesis and study of difficult peptides, proteins, and glycoproteins and will provide more opportunities for the optimization of protein biopharmaceuticals and for the development of cell-permeable biomolecules.
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56
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Andreotti G, Vitale RM, Avidan-Shpalter C, Amodeo P, Gazit E, Motta A. Converting the highly amyloidogenic human calcitonin into a powerful fibril inhibitor by three-dimensional structure homology with a non-amyloidogenic analogue. J Biol Chem 2011; 286:2707-18. [PMID: 21078667 PMCID: PMC3024767 DOI: 10.1074/jbc.m110.182014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 10/21/2010] [Indexed: 12/25/2022] Open
Abstract
Irreversible aggregation limits bioavailability and therapeutic activity of protein-based drugs. Here we show that an aggregation-resistant mutant can be engineered by structural homology with a non-amyloidogenic analogue and that the aggregation-resistant variant may act as an inhibitor. This strategy has successfully been applied to the amyloidogenic human calcitonin (hCT). Including only five residues from the non-amyloidogenic salmon calcitonin (sCT), we obtained a variant, polar human calcitonin (phCT), whose solution structure was shown by CD, NMR, and calculations to be practically identical to that of sCT. phCT was also observed to be a potent amyloidogenesis inhibitor of hCT when mixed with it in a 1:1 ratio. Fibrillation studies of phCT and the phCT-hCT mixture mimicked the sCT behavior in the kinetics and shapes of the fibrils with a dramatic reduction with respect to hCT. Finally, the effect of phCT alone and of the mixture on the intracellular cAMP level in T47D cells confirmed for the mutant and the mixture their calcitonin-like activity, exhibiting stimulation effects identical to those of sCT, the current therapeutic form. The strategy followed appears to be suitable to develop new forms of hCT with a striking reduction of aggregation and improved activity. Finally, the inhibitory properties of the aggregation-resistant analogue, if confirmed for other amyloidogenic peptides, may favor a new strategy for controlling fibril formation in a variety of human diseases.
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Affiliation(s)
- Giuseppina Andreotti
- From the Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Edificio A, 80078 Pozzuoli (Naples), Italy and
| | - Rosa Maria Vitale
- From the Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Edificio A, 80078 Pozzuoli (Naples), Italy and
| | - Carmit Avidan-Shpalter
- the Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Pietro Amodeo
- From the Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Edificio A, 80078 Pozzuoli (Naples), Italy and
| | - Ehud Gazit
- the Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Andrea Motta
- From the Istituto di Chimica Biomolecolare, Consiglio Nazionale delle Ricerche, Comprensorio Olivetti, Edificio A, 80078 Pozzuoli (Naples), Italy and
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57
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PK/PD modelling of comb-shaped PEGylated salmon calcitonin conjugates of differing molecular weights. J Control Release 2010; 149:126-32. [PMID: 20946924 DOI: 10.1016/j.jconrel.2010.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 09/29/2010] [Accepted: 10/03/2010] [Indexed: 11/23/2022]
Abstract
Salmon calcitonin (sCT) was conjugated via cysteine-1 to novel comb-shaped end-functionalised (poly(PEG) methyl ether methacrylate) (sCT-P) polymers, to yield conjugates of total molecular weights (MW) inclusive of sCT: 6.5, 9.5, 23 and 40kDa. The conjugates were characterised by HPLC and their in vitro and in vivo bioactivity was measured by cAMP assay on human T47D cells and following intravenous (i.v.) injection to rats, respectively. Stability against endopeptidases, rat serum and liver homogenates was assessed. There were linear and exponential relationships between conjugate MW with potency and efficacy respectively, however the largest MW conjugate still retained 70% of E(max) and an EC(50) of 3.7nM. In vivo, while free sCT and the conjugates reduced serum [calcium] to a maximum of 15-30% over 240 min, the half-life (T(1/2)) was increased and the area under the curve (AUC) was extended in proportion to conjugate MW. Likewise, the polymer conferred protection on sCT against attack by trypsin, chymotrypsin, elastase, rat serum and liver homogenates, with the best protection afforded by sCT-P (40kDa). Mathematical modelling accurately predicted the MW relationships to in vitro efficacy, potency, in vivo PK and enzymatic stability. With a significant increase in T(1/2) for sCT, the 40kDa MW comb-shaped PEG conjugate of sCT may have potential as a long-acting injectable formulation.
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58
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Cheng WP, Thompson C, Ryan SM, Aguirre T, Tetley L, Brayden DJ. In vitro and in vivo characterisation of a novel peptide delivery system: amphiphilic polyelectrolyte-salmon calcitonin nanocomplexes. J Control Release 2010; 147:289-97. [PMID: 20705108 DOI: 10.1016/j.jconrel.2010.07.128] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 07/29/2010] [Accepted: 07/31/2010] [Indexed: 11/16/2022]
Abstract
The cationic peptide, salmon calcitonin (sCT) was complexed with the cationic amphiphilic polyelectrolyte, poly(allyl)amine, grafted with palmitoyl and quaternary ammonium moieties at pH 5.0 and 7.4 to yield particulates (sCT-QPa). The complexes were approximately 200 nm in diameter, had zeta potentials ranging from +20 to +50 mV, and had narrow polydispersity indices (PDIs). Differential scanning calorimetry revealed the presence of an interaction between sCT and QPa in the complexes. Electron microscopy confirmed the zeta-size data and revealed a vesicular bilayer structure with an aqueous core. Tyrosine- and Nile red fluorescence indicated that the complexes retained gross physical stability for up to 7 days, but that the pH 5.0 complexes were more stable. The complexes were more resistant to peptidases, serum and liver homogenates compared to free sCT. In vitro bioactivity was measured by cAMP production in T47D cells and the complexes had EC50 values in the nM range. While free sCT was unable to generate cAMP following storage for 7 days, the complexes retained approximately 33% activity. When the complexes were injected intravenously to rats, free and complexed sCT (pH 5.0 and 7.4) but not QPa reduced serum calcium over 120 min. Free and complexed sCT but not QPa also reduced serum calcium over 240 min following intra-jejunal administration. In conclusion, sCT-QPa nanocomplexes that have been synthesised are stable, bioactive and resistant to a range of peptidases. These enhanced features suggest that they may have the potential for improved efficacy when formulated for injected and oral delivery.
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Affiliation(s)
- Woei-Ping Cheng
- School of Pharmacy, University of Hertfordshire, College Lane Hatfield AL10 9AB, UK
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59
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Wu SJ, Luo J, O'Neil KT, Kang J, Lacy ER, Canziani G, Baker A, Huang M, Tang QM, Raju TS, Jacobs SA, Teplyakov A, Gilliland GL, Feng Y. Structure-based engineering of a monoclonal antibody for improved solubility. Protein Eng Des Sel 2010; 23:643-51. [PMID: 20543007 DOI: 10.1093/protein/gzq037] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein aggregation is of great concern to pharmaceutical formulations and has been implicated in several diseases. We engineered an anti-IL-13 monoclonal antibody CNTO607 for improved solubility. Three structure-based engineering approaches were employed in this study: (i) modifying the isoelectric point (pI), (ii) decreasing the overall surface hydrophobicity and (iii) re-introducing an N-linked carbohydrate moiety within a complementarity-determining region (CDR) sequence. A mutant was identified with a modified pI that had a 2-fold improvement in solubility while retaining the binding affinity to IL-13. Several mutants with decreased overall surface hydrophobicity also showed moderately improved solubility while maintaining a similar antigen affinity. Structural studies combined with mutagenesis data identified an aggregation 'hot spot' in heavy-chain CDR3 (H-CDR3) that contains three residues ((99)FHW(100a)). The same residues, however, were found to be essential for high affinity binding to IL-13. On the basis of the spatial proximity and germline sequence, we reintroduced the consensus N-glycosylation site in H-CDR2 which was found in the original antibody, anticipating that the carbohydrate moiety would shield the aggregation 'hot spot' in H-CDR3 while not interfering with antigen binding. Peptide mapping and mass spectrometric analysis revealed that the N-glycosylation site was generally occupied. This variant showed greatly improved solubility and bound to IL-13 with affinity similar to CNTO607 without the N-linked carbohydrate. All three engineering approaches led to improved solubility and adding an N-linked carbohydrate to the CDR was the most effective route for enhancing the solubility of CNTO607.
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Affiliation(s)
- Sheng-Jiun Wu
- Biologics Research, Centocor R&D, 145 King of Prussia Radnor, PA 19087-4557, USA.
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60
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Prymula K, Sałapa K, Roterman I. "Fuzzy oil drop" model applied to individual small proteins built of 70 amino acids. J Mol Model 2010; 16:1269-82. [PMID: 20084418 DOI: 10.1007/s00894-009-0639-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 12/07/2009] [Indexed: 12/25/2022]
Abstract
The proteins composed of short polypeptides (about 70 amino acid residues) representing the following functional groups (according to PDB notation): growth hormones, serine protease inhibitors, antifreeze proteins, chaperones and proteins of unknown function, were selected for structural and functional analysis. Classification based on the distribution of hydrophobicity in terms of deficiency/excess as the measure of structural and functional specificity is presented. The experimentally observed distribution of hydrophobicity in the protein body is compared to the idealized one expressed by a three-dimensional Gauss function. The differences between these two distributions reveal the specificity of structural/functional characteristics of the protein. The residues of hydrophobicity deficiency versus the idealized distribution are assumed to indicate cavities with the potential to bind ligands, while the residues of hydrophobicity excess are interpreted as potentially participating in protein-protein complexation. The distribution of hydrophobicity irregularity seems to be specific for particular structures and functions of proteins. A comparative analysis of such profiles is carried out to identify the potential biological activity of proteins of unknown function.
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Affiliation(s)
- Katarzyna Prymula
- Department of Bioinformatics, Telemedicine Jagiellonian University - Collegium Medicum, Lazarza 16, 31-530, Krakow, Poland
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61
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Atsumi S, Wu TY, Eckl EM, Hawkins SD, Buelter T, Liao JC. Engineering the isobutanol biosynthetic pathway in Escherichia coli by comparison of three aldehyde reductase/alcohol dehydrogenase genes. Appl Microbiol Biotechnol 2009; 85:651-7. [PMID: 19609521 PMCID: PMC2802489 DOI: 10.1007/s00253-009-2085-6] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2009] [Revised: 06/02/2009] [Accepted: 06/06/2009] [Indexed: 11/29/2022]
Abstract
Biofuels synthesized from renewable resources are of increasing interest because of global energy and environmental problems. We have previously demonstrated production of higher alcohols from Escherichia coli using a 2-keto acid-based pathway. Here, we have compared the effect of various alcohol dehydrogenases (ADH) for the last step of the isobutanol production. E. coli has the yqhD gene which encodes a broad-range ADH. Isobutanol production significantly decreased with the deletion of yqhD, suggesting that the yqhD gene on the genome contributed to isobutanol production. The adh genes of two bacteria and one yeast were also compared in E. coli harboring the isobutanol synthesis pathway. Overexpression of yqhD or adhA in E. coli showed better production than ADH2, a result confirmed by activity measurements with isobutyraldehyde.
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Affiliation(s)
- Shota Atsumi
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA 90095, USA
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62
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Nanga RPR, Brender JR, Xu J, Hartman K, Subramanian V, Ramamoorthy A. Three-dimensional structure and orientation of rat islet amyloid polypeptide protein in a membrane environment by solution NMR spectroscopy. J Am Chem Soc 2009; 131:8252-61. [PMID: 19456151 PMCID: PMC4163022 DOI: 10.1021/ja9010095] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Islet amyloid polypeptide (IAPP or amylin) is a 37-residue peptide hormone associated with glucose metabolism that is cosecreted with insulin by beta-cells in the pancreas. Since human IAPP is a highly amyloidogenic peptide, it has been suggested that the formation of IAPP amyloid fibers is responsible for the death of beta-cells during the early stages of type II diabetes. It has been hypothesized that transient membrane-bound alpha-helical structures of human IAPP are precursors to the formation of these amyloid deposits. On the other hand, rat IAPP forms transient alpha-helical structures but does not progress further to form amyloid fibrils. To understand the nature of this intermediate state and the difference in toxicity between the rat and human versions of IAPP, we have solved the high-resolution structure of rat IAPP in the membrane-mimicking detergent micelles composed of dodecylphosphocholine. The structure is characterized by a helical region spanning the residues A5 to S23 and a disordered C-terminus. A distortion in the helix is seen at R18 and S19 that may be involved in receptor binding. Paramagnetic quenching NMR experiments indicate that rat IAPP is bound on the surface of the micelle, in agreement with other nontoxic forms of IAPP. A comparison to the detergent-bound structures of other IAPP variants indicates that the N-terminal region may play a crucial role in the self-association and toxicity of IAPP by controlling access to the putative dimerization interface on the hydrophobic face of the amphipathic helix.
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63
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Prymula K, Roterman I. Functional Characteristics of Small Proteins (70 Amino Acid Residues) Forming Protein-Nucleic Acid Complexes. J Biomol Struct Dyn 2009; 26:663-77. [DOI: 10.1080/07391102.2009.10507280] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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64
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Buell AK, Tartaglia GG, Birkett NR, Waudby CA, Vendruscolo M, Salvatella X, Welland ME, Dobson CM, Knowles TPJ. Position-Dependent Electrostatic Protection against Protein Aggregation. Chembiochem 2009; 10:1309-12. [DOI: 10.1002/cbic.200900144] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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65
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Ryan SM, Wang X, Mantovani G, Sayers CT, Haddleton DM, Brayden DJ. Conjugation of salmon calcitonin to a combed-shaped end functionalized poly(poly(ethylene glycol) methyl ether methacrylate) yields a bioactive stable conjugate. J Control Release 2009; 135:51-9. [PMID: 19168100 DOI: 10.1016/j.jconrel.2008.12.014] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 12/11/2008] [Accepted: 12/17/2008] [Indexed: 11/19/2022]
Abstract
Salmon calcitonin (sCT) was conjugated via its N-terminal cysteine to a comb-shaped end-functionalized poly(poly(ethylene glycol) methyl ether methacrylate) (PolyPEG, 6.5 kDa), and to linear PEG (5 kDa). Conjugate molecular weight and purity was assessed by SEC-HPLC and MALDI-TOF MS. Bioactivity of conjugates was measured by cyclic AMP assay in T47D cells. Calcium and calcitonin levels were measured in rats following intravenous injections. Stability of conjugates was tested against serine proteases, intestinal and liver homogenates and serum. Cytotoxicity of conjugates was assessed by lactate dehydrogenase (LDH) assay and by haemolytic assay of rat red blood cells. Results showed that the two conjugates were of high purity with molecular weights similar to predictions. Both conjugates retained more than 85% bioactivity in vitro and had nanomolar EC(50) values similar to sCT. While both sCT-PolyPEG(6.5 K) and sCT-PEG(5 K) were resistant to metabolism by serine proteases, homogenates and serum, PolyPEG (6.5 K) was more so. Although both conjugates reduced serum calcium to levels similar to those achieved with sCT, PolyPEG(6.5 K) extended the T(1/2) and AUC of serum sCT over values achieved with sCT-PEG and sCT itself. None of PolyPEG, PEG or methacrylic acid displayed significant cytotoxicity. PolyPEG may therefore have potential to improve pharmacokinetic profiles of injected peptides.
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Affiliation(s)
- Sinéad M Ryan
- UCD School of Agriculture, Food Science and Veterinary Medicine and UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
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66
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67
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Xie X, Pashkov I, Gao X, Guerrero JL, Yeates TO, Tang Y. Rational improvement of simvastatin synthase solubility in Escherichia coli leads to higher whole-cell biocatalytic activity. Biotechnol Bioeng 2008; 102:20-8. [PMID: 18988191 DOI: 10.1002/bit.22028] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Simvastatin is the active pharmaceutical ingredient of the blockbuster cholesterol lowering drug Zocor. We have previously developed an Escherichia coli based whole-cell biocatalytic platform towards the synthesis of simvastatin sodium salt (SS) starting from the precursor monacolin J sodium salt (MJSS). The centerpiece of the biocatalytic approach is the simvastatin synthase LovD, which is highly prone to misfolding and aggregation when overexpressed from E. coli. Increasing the solubility of LovD without decreasing its catalytic activity can therefore elevate the performance of the whole-cell biocatalyst. Using a combination of homology structural prediction and site-directed mutagenesis, we identified two cysteine residues in LovD that are responsible for nonspecific intermolecular crosslinking, which leads to oligomer formation and protein aggregation. Replacement of Cys40 and Cys60 with alanine residues resulted in marked gain in both protein solubility and whole-cell biocatalytic activities. Further mutagenesis experiments converting these two residues to small or polar natural amino acids showed that C40A and C60N are the most beneficial, affording 27% and 26% increase in whole cell activities, respectively. The double mutant C40A/C60N combines the individual improvements and displayed approximately 50% increase in protein solubility and whole-cell activity. Optimized fed-batch high-cell-density fermentation of the double mutant in an E. coli strain engineered for simvastatin production quantitatively (>99%) converted 45 mM MJSS to SS within 18 h, which represents a significant improvement over the performance of wild-type LovD under identical conditions. The high efficiency of the improved whole-cell platform renders the biocatalytic synthesis of SS an attractive substitute over the existing semisynthetic routes.
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Affiliation(s)
- Xinkai Xie
- Department of Chemical and Biomolecular Engineering, University of California, 5531 Boelter Hall, 420 Westwood Plaza, UCLA, Los Angeles, California 90095, USA
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68
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Trevino SR, Scholtz J, Pace C. Measuring and Increasing Protein Solubility. J Pharm Sci 2008; 97:4155-66. [DOI: 10.1002/jps.21327] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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69
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Maji SK, Schubert D, Rivier C, Lee S, Rivier JE, Riek R. Amyloid as a depot for the formulation of long-acting drugs. PLoS Biol 2008; 6:e17. [PMID: 18254658 PMCID: PMC2225439 DOI: 10.1371/journal.pbio.0060017] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 12/13/2007] [Indexed: 12/20/2022] Open
Abstract
Amyloids are highly organized protein aggregates that are associated with both neurodegenerative diseases such as Alzheimer disease and benign functions like skin pigmentation. Amyloids self-polymerize in a nucleation-dependent manner by recruiting their soluble protein/peptide counterpart and are stable against harsh physical, chemical, and biochemical conditions. These extraordinary properties make amyloids attractive for applications in nanotechnology. Here, we suggest the use of amyloids in the formulation of long-acting drugs. It is our rationale that amyloids have the properties required of a long-acting drug because they are stable depots that guarantee a controlled release of the active peptide drug from the amyloid termini. This concept is tested with a family of short- and long-acting analogs of gonadotropin-releasing hormone (GnRH), and it is shown that amyloids thereof can act as a source for the sustained release of biologically active peptides. Amyloids are highly organized protein aggregates that are associated with both neurodegenerative diseases such as Alzheimer disease and benign functions such as skin pigmentation. Amyloids self-polymerize by recruiting their soluble protein counterpart and remain stable against harsh physical, chemical, and biochemical conditions. These extraordinary properties make amyloids attractive for applications in nanotechnology. Here, we suggest the use of amyloids in the formulation of long-acting drugs, which are active over extended periods of days and weeks. Long-acting drugs have been designed to increase patient comfort, convenience, dosage accuracy, and assurance of patient compliance for drugs that have a low oral bioavailability. It is our rationale that amyloids have the properties required of a long-acting drug because they are stable depots that guarantee a controlled release of the active peptide drug from the amyloid termini. This concept is tested with a family of short- and long-acting analogs of gonadotropin-releasing hormone, and it is shown that amyloids thereof can act as a source for the sustained release of biologically active peptides. Amyloids have the properties required of a long-acting drug because they are stable depots that guarantee a controlled release of the active peptide drug from the amyloid termini.
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Affiliation(s)
- Samir K Maji
- Structural Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - David Schubert
- Cellular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Catherine Rivier
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Soon Lee
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Jean E Rivier
- The Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Roland Riek
- Structural Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Laboratory for Physical Chemistry, Zurich, Switzerland
- * To whom correspondence should be addressed. E-mail:
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70
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Tartaglia GG, Pawar AP, Campioni S, Dobson CM, Chiti F, Vendruscolo M. Prediction of Aggregation-Prone Regions in Structured Proteins. J Mol Biol 2008; 380:425-36. [DOI: 10.1016/j.jmb.2008.05.013] [Citation(s) in RCA: 378] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 05/02/2008] [Accepted: 05/08/2008] [Indexed: 11/17/2022]
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71
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Xiao J, Burn A, Tolbert TJ. Increasing solubility of proteins and peptides by site-specific modification with betaine. Bioconjug Chem 2008; 19:1113-8. [PMID: 18498185 DOI: 10.1021/bc800063k] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Proteins and peptides with low solubility and which aggregate are often encountered in biochemical studies and in pharmaceutical applications of polypeptides. Here, we report a new strategy to improve solubility and prevent aggregation of polypeptides using site-specific modification with the small molecule betaine, which contains a quaternary ammonium moiety. Betaine was site-selectively attached to the N-termini of two aggregation-prone polypeptide models, the bacterial enzyme xanthine-guanine phosphoribosyltransferase (CG-GPRT) and the HIV entry inhibitor peptide CG-T20, utilizing native chemical ligation. N-terminal cysteines for the betaine ligation reactions were generated from His-tagged fusion proteins using TEV protease cleavage. Ligation of the betaine thioester (1) to the N-terminal cysteine-containing polypeptide models proceeded in high yield, though denaturing conditions were required for CG-T20 due to the hydrophobic nature of this peptide. CD spectroscopy and GPRT activity assays indicate that the betaine modification of CG-GPRT and CG-T20 does not significantly affect structure or activity of the polypeptides. Solubility and turbidity measurements of betaine-modified and unmodified polypeptides demonstrate that betaine modification can greatly increase solubility. Finally, it is shown that betaine-modified CG-T20 acts as an inhibitor of the aggregation of unmodified CG-T20.
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Affiliation(s)
- Junpeng Xiao
- Department of Chemistry and Interdisciplinary Biochemistry Graduate Program, Indiana University,Bloomington, Indiana 47405, USA
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72
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Leader B, Baca QJ, Golan DE. Protein therapeutics: a summary and pharmacological classification. Nat Rev Drug Discov 2008; 7:21-39. [PMID: 18097458 DOI: 10.1038/nrd2399] [Citation(s) in RCA: 1362] [Impact Index Per Article: 85.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Once a rarely used subset of medical treatments, protein therapeutics have increased dramatically in number and frequency of use since the introduction of the first recombinant protein therapeutic--human insulin--25 years ago. Protein therapeutics already have a significant role in almost every field of medicine, but this role is still only in its infancy. This article overviews some of the key characteristics of protein therapeutics, summarizes the more than 130 protein therapeutics used currently and suggests a new classification of these proteins according to their pharmacological action.
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Affiliation(s)
- Benjamin Leader
- Department of Emergency Medicine, Brown Medical School, 593 Eddy Street, Providence, Rhode Island 02093, USA
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73
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74
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Knowles TPJ, Shu W, Devlin GL, Meehan S, Auer S, Dobson CM, Welland ME. Kinetics and thermodynamics of amyloid formation from direct measurements of fluctuations in fibril mass. Proc Natl Acad Sci U S A 2007; 104:10016-21. [PMID: 17540728 PMCID: PMC1891240 DOI: 10.1073/pnas.0610659104] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Indexed: 12/23/2022] Open
Abstract
Aggregation of proteins and peptides is a widespread and much-studied problem, with serious implications in contexts ranging from biotechnology to human disease. An understanding of the proliferation of such aggregates under specific conditions requires a quantitative knowledge of the kinetics and thermodynamics of their formation; measurements that to date have remained elusive. Here, we show that precise determination of the growth rates of ordered protein aggregates such as amyloid fibrils can be achieved through real-time monitoring, using a quartz crystal oscillator, of the changes in the numbers of molecules in the fibrils from variations in their masses. We show further that this approach allows the effect of other molecular species on fibril growth to be characterized quantitatively. This method is widely applicable, and we illustrate its power by exploring the free-energy landscape associated with the conversion of the protein insulin to its amyloid form and elucidate the role of a chemical chaperone and a small heat shock protein in inhibiting the aggregation reaction.
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Affiliation(s)
- Tuomas P. J. Knowles
- *Nanoscience Centre, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FF, United Kingdom
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom; and
| | - Wenmiao Shu
- *Nanoscience Centre, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FF, United Kingdom
| | - Glyn L. Devlin
- *Nanoscience Centre, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FF, United Kingdom
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Sarah Meehan
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Stefan Auer
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Christopher M. Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Mark E. Welland
- *Nanoscience Centre, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FF, United Kingdom
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75
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Cellmer T, Bratko D, Prausnitz JM, Blanch HW. Protein aggregation in silico. Trends Biotechnol 2007; 25:254-61. [PMID: 17433843 PMCID: PMC2680282 DOI: 10.1016/j.tibtech.2007.03.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Revised: 02/22/2007] [Accepted: 03/29/2007] [Indexed: 10/23/2022]
Abstract
Protein aggregation is a challenge to the successful manufacture of protein therapeutics; it can impose severe limitations on purification yields and compromise formulation stability. Advances in computer power, and the wealth of computational studies pertaining to protein folding, have facilitated the development of molecular simulation as a tool to investigate protein misfolding and aggregation. Here, we highlight the successes of protein aggregation studies carried out in silico, with a particular emphasis on studies related to biotechnology. To conclude, we discuss future prospects for the field, and identify several biotechnology-related problems that would benefit from molecular simulation.
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Affiliation(s)
- Troy Cellmer
- National Institutes of Health, Bethesda, MD 20892, USA
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76
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Tartaglia GG, Pechmann S, Dobson CM, Vendruscolo M. Life on the edge: a link between gene expression levels and aggregation rates of human proteins. Trends Biochem Sci 2007; 32:204-6. [PMID: 17419062 DOI: 10.1016/j.tibs.2007.03.005] [Citation(s) in RCA: 211] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 02/22/2007] [Accepted: 03/21/2007] [Indexed: 10/23/2022]
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77
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AGGRESCAN: a server for the prediction and evaluation of "hot spots" of aggregation in polypeptides. BMC Bioinformatics 2007; 8:65. [PMID: 17324296 PMCID: PMC1828741 DOI: 10.1186/1471-2105-8-65] [Citation(s) in RCA: 731] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 02/27/2007] [Indexed: 01/08/2023] Open
Abstract
Background Protein aggregation correlates with the development of several debilitating human disorders of growing incidence, such as Alzheimer's and Parkinson's diseases. On the biotechnological side, protein production is often hampered by the accumulation of recombinant proteins into aggregates. Thus, the development of methods to anticipate the aggregation properties of polypeptides is receiving increasing attention. AGGRESCAN is a web-based software for the prediction of aggregation-prone segments in protein sequences, the analysis of the effect of mutations on protein aggregation propensities and the comparison of the aggregation properties of different proteins or protein sets. Results AGGRESCAN is based on an aggregation-propensity scale for natural amino acids derived from in vivo experiments and on the assumption that short and specific sequence stretches modulate protein aggregation. The algorithm is shown to identify a series of protein fragments involved in the aggregation of disease-related proteins and to predict the effect of genetic mutations on their deposition propensities. It also provides new insights into the differential aggregation properties displayed by globular proteins, natively unfolded polypeptides, amyloidogenic proteins and proteins found in bacterial inclusion bodies. Conclusion By identifying aggregation-prone segments in proteins, AGGRESCAN shall facilitate (i) the identification of possible therapeutic targets for anti-depositional strategies in conformational diseases and (ii) the anticipation of aggregation phenomena during storage or recombinant production of bioactive polypeptides or polypeptide sets.
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78
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Trevino SR, Scholtz JM, Pace CN. Amino acid contribution to protein solubility: Asp, Glu, and Ser contribute more favorably than the other hydrophilic amino acids in RNase Sa. J Mol Biol 2007; 366:449-60. [PMID: 17174328 PMCID: PMC2771383 DOI: 10.1016/j.jmb.2006.10.026] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 09/29/2006] [Accepted: 10/08/2006] [Indexed: 10/23/2022]
Abstract
Poor protein solubility is a common problem in high-resolution structural studies, formulation of protein pharmaceuticals, and biochemical characterization of proteins. One popular strategy to improve protein solubility is to use site-directed mutagenesis to make hydrophobic to hydrophilic mutations on the protein surface. However, a systematic investigation of the relative contributions of all 20 amino acids to protein solubility has not been done. Here, 20 variants at the completely solvent-exposed position 76 of ribonuclease (RNase) Sa are made to compare the contributions of each amino acid. Stability measurements were also made for these variants, which occur at the i+1 position of a type II beta-turn. Solubility measurements in ammonium sulfate solutions were made at high positive net charge, low net charge, and high negative net charge. Surprisingly, there was a wide range of contributions to protein solubility even among the hydrophilic amino acids. The results suggest that aspartic acid, glutamic acid, and serine contribute significantly more favorably than the other hydrophilic amino acids especially at high net charge. Therefore, to increase protein solubility, asparagine, glutamine, or threonine should be replaced with aspartic acid, glutamic acid or serine.
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Affiliation(s)
- Saul R. Trevino
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843, USA
| | - J. Martin Scholtz
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - C. Nick Pace
- Department of Molecular and Cellular Medicine, Texas A&M University, College Station, Texas 77843, USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
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79
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Bieglmayer C, Vierhapper H, Dudczak R, Niederle B. Measurement of calcitonin by immunoassay analyzers. Clin Chem Lab Med 2007; 45:662-6. [PMID: 17484631 DOI: 10.1515/cclm.2007.124] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Since Nichols Institute Diagnostics (NID) ended production of their automated calcitonin immunoassay, evaluation of an alternative calcitonin assay was necessary. METHODS Calcitonin measured by the NID procedure was compared with a test from Diagnostic Products Corporation (DPC). Calcitonin was also measured by assays from DiaSorin (DS) and Scantibodies (SC). RESULTS In 187 samples, detection failed either by NID (39%) or DPC (96%) assay; in 35% of samples, the tests agreed for non-measurable calcitonin. The regression line DPC=0.78 x NID-0.3 (r=0.998) fitted results from 236 samples with detectable calcitonin. A linear relationship, albeit with scattering at low concentrations, was observed. Importantly, stimulation by pentagastrin above basal calcitonin concentrations yielded similar results with both assays. Comparisons (DPC=0.80 x DS-3.4 and DPC=0.81 x SC-1.1) confirmed an aberrant calibration of the DPC test. To overcome the method bias, we propose a multiplication factor of 0.8 to convert NID to DPC results. CONCLUSIONS Apparently due to non-specific effects, the DS and SC assays produced calcitonin results in samples from completely thyroidectomized patients, while the DPC assay correctly failed to detect calcitonin. Thus, the DPC assay on an Immulite 2000 analyzer may be used as a more accurate substitute for NID if the different calibration is noted.
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Affiliation(s)
- Christian Bieglmayer
- Clinical Institute for Medical and Chemical Laboratory Diagnostics, General Hospital of the Medical University and City of Vienna, Vienna, Austria.
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80
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Avidan-Shpalter C, Gazit E. The early stages of amyloid formation: biophysical and structural characterization of human calcitonin pre-fibrillar assemblies. Amyloid 2006; 13:216-25. [PMID: 17107882 DOI: 10.1080/13506120600960643] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Amyloid fibril formation is a nucleation dependent process characterized by a lag-phase prior to the appearance of detectable amyloid fibrils. While the three-dimensional structure of amyloid fibrils at atomic resolution is just beginning to be elucidated, the early process of monomers assembly into oligomers is less understood. Understanding the dynamic processes that lead to the formation of these intermediates is highly important as these assemblies might be the most pathological ones. Here, we investigated the biophysical and structural features characterizing the early stage assemblies formed by the human hormone calcitonin. We calculated the initial nucleus size by experimentally determining the dependence between the lag-time length and the hCT concentrations. We used size exclusion chromatography and dynamic light scattering in order to characterize the dynamic growth process of preliminary intermediates transformed into larger structures. The early structures were visualized using high-resolution transmission electron microscopy. Annular pore-like structures were observed along with protofibrilar structures. This observed morphology is similar to structures revealed during the fibrillization processes of beta-amyloid, alpha-synuclein, and islet amyloid polypeptide, suggesting that these intermediates represent a generic early structure conformation. The results introduced here imply that a variety of intermediate assemblies are formed during the early stages of amyloid fibril formation. The characterizing of their structural features and assembly kinetics will contribute to the rational design of inhibitors directed towards early structure assemblies.
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Affiliation(s)
- Carmit Avidan-Shpalter
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
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81
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Ho MR, Lou YC, Lin WC, Lyu PC, Huang WN, Chen C. Human pancreatitis-associated protein forms fibrillar aggregates with a native-like conformation. J Biol Chem 2006; 281:33566-76. [PMID: 16963458 DOI: 10.1074/jbc.m604513200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human pancreatitis-associated protein was identified in pathognomonic lesions of Alzheimer disease, a disease characterized by the presence of filamentous protein aggregates. Here, we showed that at physiological pH, human pancreatitis-associated protein forms non-Congo Red-binding, proteinase K-resistant fibrillar aggregates with diameters from 6 up to as large as 68 nm. Interestingly, circular dichroism and Fourier transform infrared spectra showed that, unlike typical amyloid fibrils, which have a cross-beta-sheet structure, these aggregates have a very similar secondary structure to that of the native protein, which is composed of two alpha-helices and eight beta-strands, as determined by NMR techniques. Surface structure analysis showed that the positively charged and negatively charged residues were clustered on opposite sides, and strong electrostatic interactions between molecules were therefore very likely, which was confirmed by cross-linking experiments. In addition, several hydrophobic residues were found to constitute a continuous hydrophobic surface. These results and protein aggregation prediction using the TANGO algorithm led us to synthesize peptide Thr(84) to Ser(116), which, very interestingly, was found to form amyloid-like fibrils with a cross-beta structure. Thus, our data suggested that human pancreatitis-associated protein fibrillization is initiated by protein aggregation primarily because of electrostatic interactions, and the loop from residues 84 to 116 may play an important role in the formation of fibrillar aggregates with a native-like conformation.
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MESH Headings
- Amino Acid Sequence
- Antigens, Neoplasm/chemistry
- Antigens, Neoplasm/genetics
- Antigens, Neoplasm/metabolism
- Antigens, Neoplasm/ultrastructure
- Biomarkers, Tumor/chemistry
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Circular Dichroism
- Congo Red
- Humans
- Hydrogen-Ion Concentration
- Lectins, C-Type/chemistry
- Lectins, C-Type/genetics
- Lectins, C-Type/metabolism
- Lectins, C-Type/ultrastructure
- Magnetic Resonance Spectroscopy
- Microscopy, Atomic Force
- Microscopy, Electron, Transmission
- Models, Molecular
- Molecular Sequence Data
- Pancreatitis-Associated Proteins
- Protein Kinases/metabolism
- Protein Structure, Tertiary
- Sequence Alignment
- Sequence Homology, Amino Acid
- Solubility
- Structural Homology, Protein
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Affiliation(s)
- Meng-Ru Ho
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
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82
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Matysiak S, Clementi C. Minimalist protein model as a diagnostic tool for misfolding and aggregation. J Mol Biol 2006; 363:297-308. [PMID: 16959265 DOI: 10.1016/j.jmb.2006.07.088] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 07/25/2006] [Accepted: 07/28/2006] [Indexed: 11/24/2022]
Abstract
We propose a realistic coarse-grained protein model and a technique to "anchor" the model to available experimental data. We apply this procedure to characterize the effect of multiple mutations on the folding mechanism of protein S6. We show that the mutation of a few "gatekeeper" residues triggers significant changes on the folding landscape of S6. These results suggest that gatekeeper residues control the flexibility of critical regions of S6, that in turn regulates the delicate balance between folding and aggregation. Although obtained with a minimalist protein model, these results are fully consistent with experimental evidence and offer a clue to understand the interplay between folding and aggregation in protein S6.
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Affiliation(s)
- Silvina Matysiak
- Department of Chemistry, Rice University, 6100 Main Street, Houston, TX 77005, USA
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83
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De Jong KL, Incledon B, Yip CM, DeFelippis MR. Amyloid fibrils of glucagon characterized by high-resolution atomic force microscopy. Biophys J 2006; 91:1905-14. [PMID: 16766610 PMCID: PMC1544305 DOI: 10.1529/biophysj.105.077438] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Glucagon solutions at pH 2.0 were subjected to mechanical agitation at 37 degrees C in the presence of a hydrophobic surface to explore the details of aggregation and fiber formation. High-resolution intermittent-contact atomic force microscopy performed in solution revealed the presence of aggregates after 0.5 h; however, longer agitation times resulted in the formation of fibrillated structures with varying levels of higher-order assembly. Height, periodicity, and amplitude measurements of these structures allowed the identification of four distinct fiber types. The most elementary fiber form, designated a filament, self-associates in a specific wound fashion to produce protofibrils composed of two filaments. Subsequent self-assembly of these filaments and protofibrils leads to two well-defined fibrillar motifs, termed Type I and Type II. Atomic force microscopy imaging of pH 2.8 glucagon solutions not agitated or exposed to elevated temperature revealed the presence of amorphous aggregates before the formation of fibrillar structures similar to those seen at pH 2.0. Time-course solution Fourier transform infrared spectroscopy and thioflavin T binding studies suggested that glucagon aggregation and fibril formation were associated with the development of beta-sheet structure. The results of these studies are used to describe a possible mechanism for glucagon aggregation and fibrillation that is consistent with a hierarchical assembly model proposed for amyloid fibril formation.
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Affiliation(s)
- Kathy L De Jong
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA
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84
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Malavolta L, Pinto MRS, Cuvero JH, Nakaie CR. Interpretation of the dissolution of insoluble peptide sequences based on the acid-base properties of the solvent. Protein Sci 2006; 15:1476-88. [PMID: 16731981 PMCID: PMC2242547 DOI: 10.1110/ps.051956206] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 02/06/2006] [Accepted: 02/27/2006] [Indexed: 10/24/2022]
Abstract
The dissolution process of model insoluble peptide sequences was investigated in view of the electron acceptor (AN) and electron donor (DN) solvent properties. The Alzheimer's disease-inducing (1-42) Abeta-amyloid peptide and its (1-21) fragment, the (66-97) transmembrane bradykinin B2 receptor sequence, and the strongly aggregated VVLGAAIV were selected as models of insoluble peptides. Solvents presenting similar AN and DN values failed, despite their polarities, to dissociate peptide chains (free in solution or bound to a polymer). The maximum solubility of these aggregated sequences was attained in solvents presenting the highest possible (AN-DN) values (in positive or negative mode). The AN-DN values ranged from approximately -20 to +80 and, notably, the lowest dissociation power was ascribed to solvents presenting values of approximately +40. The strong hydrogen bond donor water is located in this region, indicating that, for dissociation of specific insoluble segments, the solvent should appropriately combine its acid/base strength with the potential for van der Waals interactions. We also observed a sequence-dependent pH effect on peptide solubility confirmed through circular dichroism spectroscopy. This approach also revealed a complex but, in many cases, consistent influence of peptide conformation on its solubility degree, even when structure-inducing solvents were added. In conclusion, the random method of selecting solvents to dissolve insoluble and intractable peptide sequences, still in use by some, could be partially supplanted by the strategy described herein, which may be also applicable to other solute dissociation processes.
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Affiliation(s)
- Luciana Malavolta
- Department of Biophysics, Universidade Federal de São Paulo, CEP 04044-020, São Paulo, Brazil
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85
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Bratko D, Cellmer T, Prausnitz JM, Blanch HW. Effect of single-point sequence alterations on the aggregation propensity of a model protein. J Am Chem Soc 2006; 128:1683-91. [PMID: 16448142 DOI: 10.1021/ja056837h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sequences of contemporary proteins are believed to have evolved through a process that optimized their overall fitness, including their resistance to deleterious aggregation. Biotechnological processing may expose therapeutic proteins to conditions that are much more conducive to aggregation than those encountered in a cellular environment. An important task of protein engineering is to identify alternative sequences that would protect proteins when processed at high concentrations without altering their native structure associated with specific biological function. Our computational studies exploit parallel tempering simulations of coarse-grained model proteins to demonstrate that isolated amino acid residue substitutions can result in significant changes in the aggregation resistance of the protein in a crowded environment while retaining protein structure in isolation. A thermodynamic analysis of protein clusters subject to competing processes of folding and association shows that moderate mutations can produce effects similar to those caused by changes in system conditions, including temperature, concentration, and solvent composition, that affect the aggregation propensity. The range of conditions where a protein can resist aggregation can therefore be tuned by sequence alterations, although the protein generally may retain its generic ability for aggregation.
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Affiliation(s)
- Dusan Bratko
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, USA.
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86
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Yan LM, Tatarek-Nossol M, Velkova A, Kazantzis A, Kapurniotu A. Design of a mimic of nonamyloidogenic and bioactive human islet amyloid polypeptide (IAPP) as nanomolar affinity inhibitor of IAPP cytotoxic fibrillogenesis. Proc Natl Acad Sci U S A 2006; 103:2046-51. [PMID: 16467158 PMCID: PMC1413694 DOI: 10.1073/pnas.0507471103] [Citation(s) in RCA: 206] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Indexed: 12/12/2022] Open
Abstract
Protein aggregation into cytotoxic oligomers and fibrils in vivo is linked to cell degeneration and the pathogenesis of >25 uncurable diseases, whereas the high aggregation propensity and insolubility of several bioactive polypeptides and proteins in vitro prevent their therapeutic use. Aggregation of human islet amyloid polypeptide (IAPP) into pancreatic amyloid is strongly associated with the pathogenesis of type II diabetes. IAPP is a 37-residue polypeptide that acts as a neuroendocrine regulator of glucose homeostasis. However, IAPP misfolds and self-associates into cytotoxic aggregates and fibrils even at nanomolar concentrations. Because IAPP aggregation causes beta-cell death and prohibits therapeutic application of IAPP in diabetes, we pursued a minimalistic chemical design approach to generate a molecular mimic of a nonamyloidogenic and bioactive IAPP conformation that would still be able to associate with IAPP and thus inhibit its fibrillogenesis and cytotoxicity. We show that the double N-methylated full length IAPP analog [(N-Me)G24, (N-Me)I26]-IAPP (IAPP-GI) is a highly soluble, nonamyloidogenic, and noncytotoxic IAPP molecular mimic and an IAPP receptor agonist. Moreover, IAPP-GI binds IAPP with low nanomolar affinity and completely blocks IAPP cytotoxic self-assembly and fibrillogenesis with activity in the low nanomolar concentration range. Importantly, IAPP-GI dissociates cytotoxic IAPP oligomers and fibrils and is able to reverse their cytotoxicity. Bifunctional soluble IAPP mimics that combine bioactivity with the ability to block and reverse IAPP cytotoxic self-assembly are promising candidates for the treatment of diabetes. Moreover, our amyloid disease inhibitor design concept may be applicable to other protein aggregation diseases.
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Affiliation(s)
- Li-Mei Yan
- Laboratory of Bioorganic and Medicinal Chemistry, Institute of Biochemistry, University Hospital of the Rheinisch–Westfälische Technische Hochschule Aachen, Pauwelstrasse 30, D-52074 Aachen, Germany
| | - Marianna Tatarek-Nossol
- Laboratory of Bioorganic and Medicinal Chemistry, Institute of Biochemistry, University Hospital of the Rheinisch–Westfälische Technische Hochschule Aachen, Pauwelstrasse 30, D-52074 Aachen, Germany
| | - Aleksandra Velkova
- Laboratory of Bioorganic and Medicinal Chemistry, Institute of Biochemistry, University Hospital of the Rheinisch–Westfälische Technische Hochschule Aachen, Pauwelstrasse 30, D-52074 Aachen, Germany
| | - Athanasios Kazantzis
- Laboratory of Bioorganic and Medicinal Chemistry, Institute of Biochemistry, University Hospital of the Rheinisch–Westfälische Technische Hochschule Aachen, Pauwelstrasse 30, D-52074 Aachen, Germany
| | - Aphrodite Kapurniotu
- Laboratory of Bioorganic and Medicinal Chemistry, Institute of Biochemistry, University Hospital of the Rheinisch–Westfälische Technische Hochschule Aachen, Pauwelstrasse 30, D-52074 Aachen, Germany
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Esteras-Chopo A, Serrano L, López de la Paz M. The amyloid stretch hypothesis: recruiting proteins toward the dark side. Proc Natl Acad Sci U S A 2005; 102:16672-7. [PMID: 16263932 PMCID: PMC1283810 DOI: 10.1073/pnas.0505905102] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A detailed understanding of the molecular events underlying the conversion and self-association of normally soluble proteins into amyloid fibrils is fundamental to the identification of therapeutic strategies to prevent or cure amyloid-related disorders. Recent investigations indicate that amyloid fibril formation is not just a general property of the polypeptide backbone depending on external factors, but that it is strongly modulated by amino acid side chains. Here, we propose and address the validation of the premise that the amyloidogenicity of a protein is indeed localized in short protein stretches (amyloid stretch hypothesis). We demonstrate that the conversion of a soluble nonamyloidogenic protein into an amyloidogenic prone molecule can be triggered by a nondestabilizing six-residue amyloidogenic insertion in a particular structural environment. Interestingly enough, although the inserted amyloid sequences clearly cause the process, the protease-resistant core of the fiber also includes short adjacent sequences from the otherwise soluble globular domain. Thus, short amyloid stretches accessible for intermolecular interactions trigger the self-assembly reaction and pull the rest of the protein into the fibrillar aggregate. The reliable identification of such amyloidogenic stretches in proteins opens the possibility of using them as targets for the inhibition of the amyloid fibril formation process.
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Break it up. Nat Rev Drug Discov 2005. [DOI: 10.1038/nrd1835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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