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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Andersson, Marlene, et al.
(författare)
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Biomimetic spinning of artificial spider silk from a chimeric minispidroin
- 2017
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Ingår i: Nature Chemical Biology. - : Nature Publishing Group. - 1552-4450 .- 1552-4469. ; 13:3, s. 262-
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Tidskriftsartikel (refereegranskat)abstract
- Herein we present a chimeric recombinant spider silk protein (spidroin) whose aqueous solubility equals that of native spider silk dope and a spinning device that is based solely on aqueous buffers, shear forces and lowered pH. The process recapitulates the complex molecular mechanisms that dictate native spider silk spinning and is highly efficient; spidroin from one liter of bacterial shake-flask culture is enough to spin a kilometer of the hitherto toughest as-spun artificial spider silk fiber.
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| 3. |
- Andersson, Marlene, et al.
(författare)
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Biomimetic spinning of artificial spider silk from a chimeric minispidroin
- 2017
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Ingår i: Nature Chemical Biology. - : Springer Science and Business Media LLC. - 1552-4450 .- 1552-4469. ; 254
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Tidskriftsartikel (refereegranskat)abstract
- Herein we present a chimeric recombinant spider silk protein (spidroin) whose aqueous solubility equals that of native spider silk dope and a spinning device that is based solely on aqueous buffers, shear forces and lowered pH. The process recapitulates the complex molecular mechanisms that dictate native spider silk spinning and is highly efficient; spidroin from one liter of bacterial shake-flask culture is enough to spin a kilometer of the hitherto toughest as-spun artificial spider silk fiber.
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| 4. |
- Arndt, D. S., et al.
(författare)
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STATE OF THE CLIMATE IN 2017
- 2018
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
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Forskningsöversikt (refereegranskat)
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| 5. |
- Gupta, Kallol, et al.
(författare)
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The role of interfacial lipids in stabilizing membrane protein oligomers
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 541:7637, s. 421-424
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Tidskriftsartikel (refereegranskat)abstract
- Oligomerization of membrane proteins in response to lipid binding has a critical role in many cell-signalling pathways(1) but is often difficult to define(2) or predict(3). Here we report the development of a mass spectrometry platform to determine simultaneously the presence of interfacial lipids and oligomeric stability and to uncover how lipids act as key regulators of membrane-protein association. Evaluation of oligomeric strength for a dataset of 125 alpha-helical oligomeric membrane proteins reveals an absence of interfacial lipids in the mass spectra of 12 membrane proteins with high oligomeric stability. For the bacterial homologue of the eukaryotic biogenic transporters (LeuT(4), one of the proteins with the lowest oligomeric stability), we found a precise cohort of lipids within the dimer interface. Delipidation, mutation of lipid-binding sites or expression in cardiolipin-deficient Escherichia coli abrogated dimer formation. Molecular dynamics simulation revealed that cardiolipin acts as a bidentate ligand, bridging across subunits. Subsequently, we show that for the Vibrio splendidus sugar transporter SemiSWEET(5), another protein with low oligomeric stability, cardiolipin shifts the equilibrium from monomer to functional dimer. We hypothesized that lipids are essential for dimerization of the Na+/H+ antiporter NhaA from E. coli, which has the lowest oligomeric strength, but not for the substantially more stable homologous Thermus thermophilus protein NapA. We found that lipid binding is obligatory for dimerization of NhaA, whereas NapA has adapted to form an interface that is stable without lipids. Overall, by correlating interfacial strength with the presence of interfacial lipids, we provide a rationale for understanding the role of lipids in both transient and stable interactions within a range of a-helical membrane proteins, including G-protein-coupled receptors.
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| 6. |
- I'Anson, John, et al.
(författare)
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The International Economy of Children's Rights : issues in translation
- 2017
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Ingår i: The International Journal of Children's Rights. - : Brill Academic Publishers. - 0927-5568 .- 1571-8182. ; 25:1, s. 50-67
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Tidskriftsartikel (refereegranskat)abstract
- The United Nations Convention on the Rights of the Child (uncrc) is an international legal text that necessitates multiple translations into national policy contexts if it is to become mobilised within professional practice. The aim of this paper is to foreground this process of translation and to identify some of the limitations inherent within present mobilisations of the uncrc. On the basis of this diagnosis, we then raise a series of ethical considerations that might inform a more critical and open-ended approach.We characterise current approaches to mobilising the uncrc as an international economy of rights and we represent this diagrammatically. This economy, we contend, involves multiple translations of the uncrc text into a series of performative demands to which adults become accountable in situations of professional practice with children and young people.We then critically analyse this economy as presently instituted and point to a number of inherent limitations. We argue that a failure to address the issue of translation from legal text to relational practice has led to a technical resolution. The potential challenge of the uncrc as an authoritative text of critique is further weakened by the promotion of a consensus thinking that privileges agreement over the complexities associated with ethical thinking. In the light of this critique, the paper identifies new lines of questioning to inform debate concerning how a children's rights agenda might be refracted differently in future.
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| 7. |
- Kronqvist, Nina, et al.
(författare)
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Efficient protein production inspired by how spiders make silk
- 2017
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Membrane proteins are targets of most available pharmaceuticals, but they are difficult to produce recombinantly, like many other aggregation-prone proteins. Spiders can produce silk proteins at huge concentrations by sequestering their aggregation-prone regions in micellar structures, where the very soluble N-terminal domain (NT) forms the shell. We hypothesize that fusion to NT could similarly solubilize non-spidroin proteins, and design a charge-reversed mutant (NT star) that is pH insensitive, stabilized and hypersoluble compared to wildtype NT. NT star-transmembrane protein fusions yield up to eight times more of soluble protein in Escherichia coli than fusions with several conventional tags. NT star enables transmembrane peptide purification to homogeneity without chromatography and manufacture of low-cost synthetic lung surfactant that works in an animal model of respiratory disease. NT star also allows efficient expression and purification of non-transmembrane proteins, which are otherwise refractory to recombinant production, and offers a new tool for reluctant proteins in general.
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| 8. |
- Landreh, Michael, et al.
(författare)
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Controlling release, unfolding and dissociation of membrane protein complexes in the gas phase through collisional cooling
- 2015
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 51:85, s. 15582-15584
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Tidskriftsartikel (refereegranskat)abstract
- Mass spectrometry of intact membrane protein complexes requires removal of the detergent micelle by collisional activation. We demonstrate that the necessary energy can be obtained by adjusting the degree of collisional cooling in the ion source. This enables us to extend the energy regime for dissociation of membrane protein complexes.
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| 9. |
- Landreh, Michael, et al.
(författare)
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Effects of Detergent Micelles on Lipid Binding to Proteins in Electrospray Ionization Mass Spectrometry
- 2017
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 89:14, s. 7425-7430
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Tidskriftsartikel (refereegranskat)abstract
- A wide variety of biological processes rely upon interactions between proteins and lipids, ranging from molecular transport to the organization of the cell membrane. It was recently established that electrospray ionization mass spectrometry (ESI-MS) is capable of capturing transient interactions between membrane proteins and their lipid environment, and a detailed understanding of the underlying processes is therefore of high importance. Here, we apply ESIMS to investigate the factors that govern complex formation in solution and gas phases by comparing nonselective lipid binding with soluble and membrane proteins. We find that exogenously added lipids did not bind to soluble proteins, suggesting that lipids have a low propensity to form electrospray ionization adducts. The presence of detergents at increasing micelle concentrations, on the other hand, resulted in moderate lipid binding to soluble proteins. A direct ESI-MS comparison of lipid binding to the soluble protein serum albumin and to the integral membrane protein NapA shows that soluble proteins acquire fewer lipid adducts. Our results suggest that protein lipid complexes form via contacts between proteins and mixed lipid/detergent micelles. For soluble proteins, these complexes arise from nonspecific contacts between the protein and detergent/lipid micelles in the electrospray droplet. For membrane proteins, lipids are incorporated into the surrounding micelle in solution, and complex formation occurs independently of the ESI process. We conclude that the lipids in the resulting complexes interact predominantly with sites located in the transmembrane segments, resulting in nativelike complexes that can be interrogated by MS.
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| 10. |
- Landreh, Michael, et al.
(författare)
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Integrating mass spectrometry with MD simulations reveals the role of lipids in Na+/H+ antiporters
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Na+/H+ antiporters are found in all kingdoms of life and exhibit catalysis rates that are among the fastest of all known secondary-active transporters. Here we combine ion mobility mass spectrometry and molecular dynamics simulations to study the conformational stability and lipid-binding properties of the Na+/H+ exchanger NapA from Thermus thermophilus and compare this to the prototypical antiporter NhaA from Escherichia coli and the human homologue NHA2. We find that NapA and NHA2, but not NhaA, form stable dimers and do not selectively retain membrane lipids. By comparing wild-type NapA with engineered variants, we show that the unfolding of the protein in the gas phase involves the disruption of inter-domain contacts. Lipids around the domain interface protect the native fold in the gas phase by mediating contacts between the mobile protein segments. We speculate that elevator-type antiporters such as NapA, and likely NHA2, use a subset of annular lipids as structural support to facilitate large-scale conformational changes within the membrane.
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