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| 2. |
- Holmner, Åsa, et al.
(författare)
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Blood group antigen recognition by Escherichia coli heat-labile enterotoxin
- 2007
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Ingår i: Journal of Molecular Biology. - London : Elsevier BV. - 0022-2836 .- 1089-8638. ; 371:3, s. 754-764
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Tidskriftsartikel (refereegranskat)abstract
- In a number of bacterial infections, such as Helicobacter pylori, Campylobacter jejuni and Vibrio cholerae infections, a correlation between the severity of disease and blood group phenotype of infected individuals has been observed. In the present investigation, we have studied the molecular basis of this effect for enterotoxigenic Escherichia coli (ETEC) infections. ETEC are non-invasive bacteria, which act through second messenger pathways to cause diarrhea. It has been suggested that the major virulence factor of ETEC from human isolates, i.e. the human heat-labile enterotoxin (hLT), recognizes certain blood group epitopes, although the molecular basis of blood group antigen recognition is unknown. The 2.5 angstrom crystal structure of the receptor-binding B-subunit of hLT in complex with the blood group A antigen analog GalNAc alpha 3(Fuc alpha-2)Gal beta 4(Fuc alpha-3)Glc beta provides evidence of a previously unknown binding site in the native toxin. The structure reveals the molecular interactions underlying blood group antigen recognition and suggests how this protein can discriminate between different blood group epitopes. These results support the previously debated role of hLT in the blood group dependence of ETEC infections. Similar observations regarding the closely related cholera toxin in V. cholera infections are also discussed. (c) 2007 Elsevier Ltd. All rights reserved.
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| 3. |
- Landreh, M., et al.
(författare)
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A pH-dependent dimer lock in spider silk protein
- 2010
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Ingår i: Journal of Molecular Biology. - : Academic Press. - 0022-2836 .- 1089-8638. ; 404:2, s. 328-336
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Tidskriftsartikel (refereegranskat)abstract
- Spider dragline silk, one of the strongest polymers in nature, is composed of proteins termed major ampullate spidroin (MaSp) 1 and MaSp2. The N-terminal (NT) domain of MaSp1 produced by the nursery web spider Euprosthenops australis acts as a pH-sensitive relay, mediating spidroin assembly at around pH 6.3. Using amide hydrogen/deuterium exchange combined with mass spectrometry (MS), we detected pH-dependent changes in deuterium incorporation into the core of the NT domain, indicating global structural stabilization at low pH. The stabilizing effects were diminished or abolished at high ionic strength, or when the surface-exposed residues Asp40 and Glu84 had been exchanged with the corresponding amides. Nondenaturing electrospray ionization MS revealed the presence of dimers in the gas phase at pH values below--but not above--6.4, indicating a tight electrostatic association that is dependent on Asp40 and Glu84 at low pH. Results from analytical ultracentrifugation support these findings. Together, the data suggest a mechanism whereby lowering the pH to <6.4 results in structural changes and alteration of charge-mediated interactions between subunits, thereby locking the spidroin NT dimer into a tight entity important for aggregation and silk formation.
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- Söderholm, Jonas, 1978, et al.
(författare)
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Impact of Soluble CD26 on Treatment Outcome and Hepatitis C Virus-Specific T Cells in Chronic Hepatitis C Virus Genotype 1 Infection
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Background Interferon and ribavirin therapy for chronic hepatitis C virus (HCV) infection yields sustained virological response (SVR) rates of 50–80%. Several factors such as non-1 genotype, beneficial IL28B genetic variants, low baseline IP-10, and the functionality of HCV-specific T cells predict SVR. With the pending introduction of new therapies for HCV entailing very rapid clearance of plasma HCV RNA, the importance of baseline biomarkers likely will increase in order to tailor therapy. CD26 (DPPIV) truncates the chemokine IP-10 into a shorter antagonistic form, and this truncation of IP-10 has been suggested to influence treatment outcome in patients with chronic HCV infection patients. In addition, previous reports have shown CD26 to be a co-stimulator for T cells. The aim of the present study was to assess the utility of CD26 as a biomarker for treatment outcome in chronic hepatitis C and to define its association with HCV-specific T cells. Methods Baseline plasma from 153 genotype 1 and 58 genotype 2/3 infected patients enrolled in an international multicenter phase III trial (DITTO-HCV) and 36 genotype 1 infected patients participating in a Swedish trial (TTG1) were evaluated regarding baseline soluble CD26 (sCD26) and the functionality of HCV-specific CD8+ T cells. Results Genotype 1 infected patients achieving SVR in the DITTO (P = 0.002) and the TTG1 (P = 0.02) studies had lower pretreatment sCD26 concentrations compared with non-SVR patients. Sixty-five percent of patients with sCD26 concentrations below 600 ng/mL achieved SVR compared with 39% of the patients with sCD26 exceeding 600 ng/mL (P = 0.01). Patients with sCD26 concentrations below 600 ng/mL had significantly higher frequencies of HCV-specific CD8+ T cells (P = 0.02). Conclusions Low baseline systemic concentrations of sCD26 predict favorable treatment outcome in chronic HCV infection and may be associated with higher blood counts of HCV-specific CD8+ T cells.
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