| 21. |
- Olofsson, Anders, et al.
(författare)
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Quenched hydrogen/deuterium exchange NMR characterization of amyloid-β peptide aggregates formed in the presence of Cu2+ or Zn2
- 2009
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Ingår i: The FEBS Journal. - : Wiley InterScience. - 1742-464X .- 1742-4658. ; 276:15, s. 4051-4060
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease, a neurodegenerative disorder causing synaptic impairment and neuronal cell death, is strongly correlated with aggregation of the amyloid-β peptide (Aβ). Divalent metal ions such as Cu2+ and Zn2+ are known to significantly affect the rate of aggregation and morphology of Aβ assemblies in vitro and are also found at elevated levels within cerebral plaques in vivo. The present investigation characterized the architecture of the aggregated forms of Aβ(1–40) and Aβ(1–42) in the presence or absence of either Cu2+ or Zn2+ using quenched hydrogen/deuterium exchange combined with solution NMR spectroscopy. The NMR analyses provide a quantitative and residue-specific structural characterization of metal-induced Aβ aggregates, showing that both the peptide sequence and the type of metal ion exert an impact on the final architecture. Common features among the metal-complexed peptide aggregates are two solvent-protected regions with an intervening minimum centered at Asn27, and a solvent-accessible N-terminal region, Asp1–Lys16. Our results suggest that Aβ in complex with either Cu2+ or Zn2+ can attain an aggregation-prone β-strand–turn–β-strand motif, similar to the motif found in fibrils, but where the metal binding to the N-terminal region guides the peptide into an assembly distinctly different from the fibril form.
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| 22. |
- Olofsson, Anders, et al.
(författare)
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The solvent protection of alzheimer amyloid-beta-(1-42) fibrils as determined by solution NMR spectroscopy.
- 2006
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Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 281:1, s. 477-83
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer disease is a neurodegenerative disorder that is tightly linked to the self-assembly and amyloid formation of the 39-43-residue-long amyloid-beta (Abeta) peptide. Considerable evidence suggests a correlation between Alzheimer disease development and the longer variants of the peptide, Abeta-(1-42/43). Currently, a molecular understanding for this behavior is lacking. In the present study, we have investigated the hydrogen/deuterium exchange of Abeta-(1-42) fibrils under physiological conditions, using solution NMR spectroscopy. The obtained residue-specific and quantitative map of the solvent protection within the Abeta-(1-42) fibril shows that there are two protected core regions, Glu11-Gly25 and Lys28-Ala42, and that the residues in between, Ser26 and Asn27, as well as those in the N terminus, Asp1-Tyr10, are solvent-accessible. This result reveals considerable discrepancies when compared with a previous investigation on Abeta-(1-40) fibrils and suggests that the additional residues in Abeta-(1-42), Ile41 and Ala42, significantly increase the solvent protection and stability of the C-terminal region Lys28-Ala42. Consequently, our findings provide a molecular explanation for the increased amyloidogenicity and toxicity of Abeta-(1-42) compared with shorter Abeta variants found in vivo.
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| 23. |
- Paracuellos, Patricia, et al.
(författare)
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Expression and purification of SfaXII, a protein involved in regulating adhesion and motility genes in extraintestinal pathogenic Escherichia coli
- 2012
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Ingår i: Protein Expression and Purification. - : Elsevier. - 1046-5928 .- 1096-0279. ; 86:2, s. 127-134
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Tidskriftsartikel (refereegranskat)abstract
- Pathogenic Escherichia coli strains commonly harbor genes involved in formation of fimbriae, such as the sfa(II) fimbrial gene cluster found in uropathogenic and newborn meningitis isolates. The sfaX(II) gene, located at the distal end of the sfa(II) operon, was recently shown to play a role in controlling virulence-related gene expression in extraintestinal pathogenic E. coli (ExPEC). Until now, detailed characterization of the SfaX(II) protein has been hampered by difficulties in obtaining large quantities of soluble protein. By a rational modeling approach, we engineered a Cys70Ser mutation, which successfully improved solubility of the protein. Here, we present the expression, purification, and initial characterization of the recombinant SfaX(IIC70S) mutant. The protein was produced in E. coli BL21 (DE3) cells grown in autoinduction culture media. The plasmid vector harbored DNA encoding the SfaX(IIC70S) protein N-terminally fused with a six histidine (H6) sequence followed by a ZZ tag (a derivative of the Staphylococcus protein A) (H6-ZZ tag). The H6-ZZ tag was cleaved off with Tobacco Etch Virus (TEV) protease and the 166 amino acid full-length homo-dimeric protein was purified using affinity and size-exclusion chromatography. Electrophoretic mobility gel shift assays and atomic force microscopy demonstrated that the protein possesses DNA-binding properties, suggesting that the transcriptional regulatory activity of SfaX(II) can be mediated via direct binding to DNA.
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| 24. |
- Uhlig, H H, et al.
(författare)
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Antibody response to dietary and autoantigens in G alpha i2-deficient mice.
- 2001
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Ingår i: European journal of gastroenterology & hepatology. - 0954-691X. ; 13:12, s. 1421-9
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Tidskriftsartikel (refereegranskat)abstract
- Mice with a targeted mutation in the G protein subunit G alpha i2 gene develop a colonic mucosal inflammation, with a highly activated B-cell response. We wanted to investigate whether this increased B-cell activity was directed against dietary antigens and/or various self tissues.
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| 25. |
- Wetterlund, Elisabeth, 1978-, et al.
(författare)
-
Smart Waste Treatment in the Circular Economy
- 2024
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Rapport (populärvet., debatt m.m.)abstract
- This project has targeted utilisation of infrastructure for organic waste treatment in Sweden, in particular sewage sludge, to achieve increased production of high-value materials and energy carriers, reduced use of primary resources, and improved economic performance. We have investigated the sewage sludge management system as a socio-technical system facing a change, with integral connections to the energy and waste systems.In conclusion, there is no silver bullet for the future of sewage sludge management. Indeed, it would have to be a full clip of silver bullets, as we found that a mishmash of different barriers –technical, economic, legal, and related to public perception – creates uncertainty that hinders progress regarding both sustainable long-term strategies and technological advancement. The Swedish sewage sludge management is largely fragmented, highlighting the need to shift directionto a more holistic approach. This can help actors address common issues rather than focussing solely on activity-specific problems. Introducing new legislation could be a key step, as the current specific legislation on sewage sludge has a seemingly insignificant role for today’s sludge management, compared to other legislation and the voluntary certification.We have formulated six overall research highlights, to outline both published results and meta-conclusions based on combined insights. Each highlight is described separately in this report.
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| 26. |
- Wikström Hultdin, Ulrika, et al.
(författare)
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Purification, crystallization and preliminary data analysis of FocB, a transcription factor regulating fimbrial adhesin expression in uropathogenic Escherichia coli
- 2010
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Ingår i: Acta Crystallographica. Section F. - 1744-3091 .- 1744-3091. ; 66:Pt 3, s. 337-341
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor FocB belongs to a family of regulators encoded by several different fimbriae gene clusters in uropathogenic Escherichia coli. Recent findings suggest that FocB-family proteins may form different protein-protein complexes and that they may exert both positive and negative effects on the transcription of fimbriae genes. However, little is known about the actual role and mode of action when these proteins interact with the fimbriae operons. The 109-amino-acid FocB transcription factor from the foc gene cluster in E. coli strain J96 has been cloned, expressed and purified. The His6-tagged fusion protein was captured by Ni2+-affinity chromatography, cleaved with tobacco etch virus protease and purified by gel filtration. The purified protein is oligomeric, most likely in the form of dimers. NMR analysis guided the crystallization attempts by showing that probable conformational exchange or oligomerization is reduced at temperatures above 293 K and that removal of the highly flexible His6 tag is advantageous. The protein was crystallized using the hanging-drop vapour-diffusion method at 295 K. A native data set to 2.0 Å resolution was collected at 100 K using synchrotron radiation.
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| 27. |
- Öhman, Lena, 1967, et al.
(författare)
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Acellular Bordetella pertussis vaccine enhances mucosal interleukin-10 production, induces apoptosis of activated Th1 cells and attenuates colitis in Galphai2-deficient mice.
- 2005
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 141:1, s. 37-46
-
Tidskriftsartikel (refereegranskat)abstract
- Mice deficient for the inhibitory G protein subunit alpha2 (Galphai2(-/-)) spontaneously develop a progressive inflammatory bowel disease resembling ulcerative colitis, and have a T helper 1 (Th1)-dominated immune response prior to onset of colitis, which is further augmented after the onset of disease. The present study was performed to investigate whether the Galphai2(-/-) mice were able to down-regulate the Th1-dominated inflammatory mucosal immune response and/or induce an anti-inflammatory Th2/T regulatory response and thereby diminish the severity of colitis following treatment with acellular Bordetella pertussis vaccine. The acellular vaccine against B. pertussis, the causative agent of whooping cough, has been demonstrated to induce a Th2-mediated response in both man and mice. We therefore treated Galphai2(-/-) mice intraperitoneally with a three-component acellular B. pertussis vaccine. The treated Galphai2(-/-) mice showed significantly increased interleukin (IL)-10 production in intestinal tissue, associated with significantly reduced colitis and decreased mortality, compared to untreated Galphai2(-/-) mice. The attenuation of colitis in Galphai2(-/-) mice was due, at least partly, to the B. pertussis surface antigen filamentous haemagglutinin (FHA), which almost completely inhibited proliferation of CD4(+) T cells and stimulated apoptosis of activated CD4(+) T helper 1 cells. In conclusion, the three-component acellular B. pertussis vaccine containing filamentous haemagglutinin increases the production of IL-10 in the intestinal mucosa, induces apoptosis of activated Th1 cells and attenuates colitis in Galphai2(-/-) mice.
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| 28. |
- Öhman, Lena, 1967, et al.
(författare)
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Immune activation in the intestinal mucosa before the onset of colitis in Galphai2-deficient mice.
- 2000
-
Ingår i: Scandinavian journal of immunology. - 0300-9475. ; 52:1, s. 80-90
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Tidskriftsartikel (refereegranskat)abstract
- G-protein subunit Galphai2-deficient mice spontaneously develop an inflammatory bowel disease that clinically and histopathologically resembles ulcerative colitis in humans. The aim of this study was to determine whether immunological changes precede the development of colitis in Galphai2-deficient mice. Therefore, Galphai2-deficient mice with no clinical or histopathological signs of colitis were compared with Galphai2-deficient mice with established colitis and wild-type animals, concerning immunological parameters. Healthy Galphai2-deficient mice displayed an increased frequency of CD4+ T cells and a decreased frequency of CD19+ B lymphocytes in the intestinal mucosa compared with control mice. The CD4+ population was characterized by a memory phenotype, i.e. increased expression of CD44 and decreased expression of CD45RB and CD62L, as well as increased expression of the mucosal homing receptors integrins alpha4beta7 and alphaEbeta7. Production of pro-inflammatory cytokines, interleukin (IL)-1beta and interferon (IFN)-gamma, were increased in Galphai2-deficient mice before clinical signs of disease were evident. In addition, total immunoglobulin (Ig)G and IgA levels in large intestinal secretions were increased significantly compared with wild-type mice, and antibodies specific for the normal intestinal flora in large intestinal secretions were present in Galphai2-deficient mice several weeks before the onset of colitis. In contrast, antibodies against tropomyosin, a putative autoantigen in human ulcerative colitis, were not found in Galphai2-deficient mice before the onset of colitis, although they were present in animals with established disease. In conclusion, activation of the intestinal immune system precedes histopathological and clinical signs of inflammation in Galphai2-deficient mice, suggesting that immune abnormalities play an important role in the induction of colitis.
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| 29. |
- Öhman, Lena, 1967, et al.
(författare)
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Impaired B cell responses to orally administered antigens in lamina propria but not Peyer's patches of Galphai2-deficient mice prior to colitis.
- 2005
-
Ingår i: Immunology. - : Wiley. - 0019-2805 .- 1365-2567. ; 115:2, s. 271-8
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Tidskriftsartikel (refereegranskat)abstract
- Despite numerous studies on the intestinal immune system in patients with inflammatory bowel disease (IBD) and animal models of IBD, very little is known about the immune reactivity of mucosal lymphocytes following oral immunizations under these circumstances. The reactivity of Peyer's patch (PP) and lamina propria (LP) T and B lymphocytes in inhibitory G-protein alpha2 subunit-deficient (Galphai2-/-) mice developing an IBD resembling ulcerative colitis was investigated following repeated oral immunizations with keyhole limpet haemocyanin (KLH), together with the adjuvant cholera toxin, prior to colitis. The antigen-specific B-cell response in the LP of both the small and the large intestines was significantly reduced in Galphai2-/- as compared to wild-type mice. In contrast, the frequency of KLH-specific immunoglobulin (Ig)-producing cells in the PP did not differ between Galphai2-/- and wild-type mice, whereas the total frequency of Ig-producing cells as well as the frequency of enteric flora-specific Ig-producing cells in the PP was significantly increased in Galphai2-/- as compared to wild-type mice. Analysis of T cell responses following restimulation ex vivo with KLH revealed a dramatic increase in the production of interferon-gamma in mesenteric lymph node, PP and LP lymphocytes from Galphai2-deficient as compared to wild-type mice, together with decreased production of interleukin-10 in all locations except the PP.
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| 30. |
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