| 1. |
- Kemp, Grant, et al.
(författare)
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Cotranslational folding cooperativity of contiguousdomains of α-spectrin
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:25, s. 14119-14126
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Tidskriftsartikel (refereegranskat)abstract
- Proteins synthesized in the cell can begin to fold during translation before the entire polypeptide has been produced, which may be particularly relevant to the folding of multidomain proteins. Here, we study the cotranslational folding of adjacent domains from the cytoskeletal protein α-spectrin using force profile analysis (FPA). Specifically, we investigate how the cotranslational folding behavior of the R15 and R16 domains are affected by their neighboring R14 and R16, and R15 and R17 domains, respectively. Our results show that the domains impact each other’s folding in distinct ways that may be important for the efficient assembly of α-spectrin, and may reduce its dependence on chaperones. Furthermore, we directly relate the experimentally observed yield of full-length protein in the FPA assay to the force exerted by the folding protein in piconewtons. By combining pulse-chase experiments to measure the rate at which the arrested protein is converted into full-length protein with a Bell model of force-induced rupture, we estimate that the R16 domain exerts a maximal force on the nascent chain of ∼15 pN during cotranslational folding.
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| 2. |
- Nilsson, Ola B., et al.
(författare)
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Cotranslational folding of spectrin domains via partially structured states
- 2017
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Ingår i: Nature Structural & Molecular Biology. - : Springer Science and Business Media LLC. - 1545-9993 .- 1545-9985. ; 24:3, s. 221-225
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Tidskriftsartikel (refereegranskat)abstract
- How do the key features of protein folding, elucidated from studies on native, isolated proteins, manifest in cotranslational folding on the ribosome? Using a well-characterized family of homologous α-helical proteins with a range of biophysical properties, we show that spectrin domains can fold vectorially on the ribosome and may do so via a pathway different from that of the isolated domain. We use cryo-EM to reveal a folded or partially folded structure, formed in the vestibule of the ribosome. Our results reveal that it is not possible to predict which domains will fold within the ribosome on the basis of the folding behavior of isolated domains; instead, we propose that a complex balance of the rate of folding, the rate of translation and the lifetime of folded or partly folded states will determine whether folding occurs cotranslationally on actively translating ribosomes.
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| 3. |
- Nilsson, Ola B., et al.
(författare)
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Cotranslational Protein Folding inside the Ribosome Exit Tunnel
- 2015
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 12:10, s. 1533-1540
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Tidskriftsartikel (refereegranskat)abstract
- At what point during translation do proteins fold? It is well established that proteins can fold cotranslationally outside the ribosome exit tunnel, whereas studies of folding inside the exit tunnel have so far detected only the formation of helical secondary structure and collapsed or partially structured folding intermediates. Here, using a combination of co-translational nascent chain force measurements, inter-subunit fluorescence resonance energy transfer studies on single translating ribosomes, molecular dynamics simulations, and cryoelectron microscopy, we show that a small zinc-finger domain protein can fold deep inside the vestibule of the ribosome exit tunnel. Thus, for small protein domains, the ribosome itself can provide the kind of sheltered folding environment that chaperones provide for larger proteins.
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| 4. |
- Nilsson, Ola B., et al.
(författare)
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Designing a Multimer Allergen for Diagnosis and Immunotherapy of Dog Allergic Patients
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dog dander extract used for diagnosis and allergen-specific immunotherapy is often of variable and of poor quality.Objective: To assemble four well-established dog allergen components into one recombinant folded protein for improved diagnosis and vaccination of allergy to dog.Methods: A linked molecule, comprising the four dog lipocalin allergens Can f 1, Can f 2, Can f 4 and Can f 6 was constructed. The tetrameric protein was structurally characterized by small angle X-ray scattering, and compared with each single recombinant lipocalin allergen or an equimolar mix of the four allergens by analytical size exclusion chromatography, circular dichroism, allergen-specific IgE in serum by ELISA and allergen-dependent capacity to activate basophils. The immunogenicity of the fusion protein was evaluated in immunized mice by assessing splenocyte proliferation and antibody production.Results: The linked tetrameric construct was produced as a soluble fusion protein, with the specific folds of the four individual allergens conserved. This multi-allergen molecule was significantly more efficient (p < 0.001) than each single recombinant allergen in binding to dog-specific IgE, and the epitope spectrum was unaffected compared to an equimolar mix of the four allergens. Basophil degranulation revealed that the biologic activity of the linked molecule was retained. Immunization of mice with the linked construct induced comparable allergen-specific IgG responses with blocking capacity towards all included allergens and generated comparably low T-cell responses.Conclusion: We provide the first evidence for a linked recombinant molecule covering the major dog allergens for potential use in diagnostics and allergy vaccination of dog allergic patients.
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| 5. |
- Nilsson, Ola B., et al.
(författare)
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Mammalian-derived respiratory allergens - Implications for diagnosis and therapy of individuals allergic to furry animals
- 2014
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Ingår i: Methods. - : Elsevier BV. - 1046-2023 .- 1095-9130. ; 66:1, s. 86-95
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Tidskriftsartikel (refereegranskat)abstract
- Furry animals cause respiratory allergies in a significant proportion of the population. A majority of all mammalian allergens are spread as airborne particles, and several have been detected in environments where furry animals are not normally kept. The repertoire of allergens from each source belongs to a restricted number of allergen families. Classification of allergen families is particularly important for the characterization of allergenicity and cross-reactivity of allergens. In fact, major mammalian allergens are taken from only three protein families, i.e. the secretoglobin, lipocalin and kallikrein families. In particular, the lipocalin superfamily harbours major allergens in all important mammalian allergen sources, and cross-reactivity between lipocalin allergens may explain cross-species sensitization between mammals. The identification of single allergen components is of importance to improve diagnosis and therapy of allergic patients using component-resolved diagnostics and allergen-specific immunotherapy (ASIT) respectively. Major disadvantages with crude allergen extracts for these applications emphasize the benefits of careful characterization of individual allergens. Furthermore, detailed knowledge of the characteristics of an allergen is crucial to formulate attenuated allergy vaccines, e.g. hypoallergens. The diverse repertoires of individual allergens from different mammalian species influence the diagnostic potential and clinical efficacy of ASIT to furry animals. As such, detailed knowledge of individual allergens is essential for adequate clinical evaluation. This review compiles current knowledge of the allergen families of mammalian species, and discusses how this information may be used for improved diagnosis and therapy of individuals allergic to mammals.
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| 6. |
- Nilsson, Ola B., et al.
(författare)
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Trigger Factor Reduces the Force Exerted on the Nascent Chain by a Cotranslationally Folding Protein
- 2016
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 428:6, s. 1356-1364
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Tidskriftsartikel (refereegranskat)abstract
- Cotranslational protein folding can generate pulling forces on the nascent chain that can affect the instantaneous translation rate and thereby possibly feed back on the folding process. Such feedback would represent a new way of coupling translation and folding, different from coupling based on, for example, codon usage. However, to date, we have carried out the experiments used to measure pulling forces generated by cotranslational protein folding either in reconstituted in vitro translation systems lacking chaperones, in ill-defined cell lysates, or in vivo; hence, the effects of chaperones on force generation by folding are unknown. Here, we have studied the cotranslational folding of dihydrofolate reductase (DHFR) in the absence and in the presence of the chaperones trigger factor (TF) and GroEL/ES. DHFR was tethered to the ribosome via a C-terminal linker of varying length, ending with the SecM translational arrest peptide that serves as an intrinsic force sensor reporting on the force generated on the nascent chain when DHFR folds. We find that DHFR folds into its native structure only when it has emerged fully outside the ribosome and that TF and GroEL alone substantially reduces the force generated on the nascent chain by the folding of DHFR, while GroEL/ES has no effect. TF therefore weakens the possible coupling between cotranslational folding and translation.
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