| 1. |
- Backmark, Anna, 1979, et al.
(författare)
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Affinity tags can reduce merohedral twinning of membrane protein crystals
- 2008
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Ingår i: Acta Crystallographica. Section D: Biological Crystallography. - 1399-0047 .- 0907-4449. ; D64, s. 1183-1186
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Tidskriftsartikel (refereegranskat)abstract
- This work presents a comparison of the crystal packing of three eukaryotic membrane proteins: human aquaporin 1, human aquaporin 5 and a spinach plasma membrane aquaporin. All were purified from expression constructs both with and without affinity tags. With the exception of tagged aquaporin 1, all constructs yielded crystals. Two significant effects of the affinity tags were observed: crystals containing a tag typically diffracted to lower resolution than those from constructs encoding the protein sequence alone and constructs without a tag frequently produced crystals that suffered from merohedral twinning. Twinning is a challenging crystallographic problem that can seriously hinder solution of the structure. Thus, for integral membrane proteins, the addition of an affinity tag may help to disrupt the approximate symmetry of the protein and thereby reduce or avoid merohedral twinning.
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| 2. |
- Nyblom, Anna Maria, 1975, et al.
(författare)
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Exceptional overproduction of a functional human membrane protein
- 2007
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928 .- 1096-0279. ; 56:1, s. 110-120
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Tidskriftsartikel (refereegranskat)abstract
- Eukaryotic-especially human-membrane protein overproduction remains a major challenge in biochemistry. Heterologously overproduced and purified proteins provide a starting point for further biochemical, biophysical and structural studies, and the lack of sufficient quantities of functional membrane proteins is frequently a bottleneck hindering this. Here, we report exceptionally high production levels of a correctly folded and crystallisable recombinant human integral membrane protein in its active form; human aquaporin 1 (hAQP1) has been heterologously produced in the membranes of the methylotrophic yeast Pichia pastoris. After solubilisation and a two step purification procedure, at least 90 mg hAQP1 per liter of culture is obtained. Water channel activity of this purified hAQP was verified by reconstitution into proteoliposomes and performing stopped-flow vesicle shrinkage measurements. Mass spectrometry confirmed the identity of hAQPI in crude membrane preparations, and also from purified protein reconstituted into proteoliposomes. Furthermore, crystallisation screens yielded diffraction quality crystals of untagged recombinant hAQP1. This study illustrates the power of the yeast P. pastoris as a host to produce exceptionally high yields of a functionally active, human integral membrane protein for subsequent functional and structural characterization. (c) 2007 Elsevier Inc. All rights reserved.
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| 3. |
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| 4. |
- Rödström, Karin, 1986, et al.
(författare)
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Structural studies of staphylococcal enterotoxin H in complex with T cell receptor and major histocompatibility complex class II
- 2010
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Ingår i: FEBS JOURNAL. - 1742-464X. ; 2010, 277, s. 53-54
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Superantigens (SAgs) are bacterial toxins capable of cross-linking the immune receptors of the host, the T cell receptor (TCR) and major histocompatibility complex (MHC) class II, and thereby trigger a massive release of cytokines. This could lead to toxic shock syndrome, which can have a fatal outcome. Here, we present the crystal structure of the ternary complex between the superantigen, staphylococcal enterotoxin H (SEH), TCR and MHC, as well as the dimer complex, including only TCR and SEH. It is evident that SEH interacts with the variable α domain (Vα) of TCR, in sharp contrast to previously studied SAgs that interact with the Vβ domain. Due to the high structural conservation of amino acids in SEH that are crucial for the interaction, we propose that in addition to Vβ activation of T cells, there are SAgs, in addition to SEH, which are able to activate T cells through Vα as well. In addition to providing crucial information regarding the nature of TCR-mediated recognition of superantigens, the finding have central implications for future strategies aimed at preventing or modulating the often pathogenic response to superantigens.
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| 5. |
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| 6. |
- Saline, Maria, et al.
(författare)
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Backbone resonance assignment of Staphylococcal Enterotoxin H.
- 2009
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Ingår i: Biomolecular NMR assignments. - : Springer Science and Business Media LLC. - 1874-270X .- 1874-2718.
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Tidskriftsartikel (refereegranskat)abstract
- The staphylococcal enterotoxin H (SEH; 217 aa, 25 kD) belongs to a family of superantigens that cause a massive immune response upon simultaneous binding to the T cell receptor (TCR) and the major histocompatibility complex class II. The SEH-TCR interaction is weak and amenable to studies using NMR methodology. Essentially, 2 mg of U{(2)H, (13)C,(15)N}-labeled SEH was used for the complete sequential backbone assignment of SEH at 900 MHz. The protein secondary structure inferred from the chemical shift index (C(alpha) and C(beta)) is in very good agreement with the secondary structure elements of the X-ray structure.
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| 7. |
- Saline, Maria, et al.
(författare)
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The structure of superantigen complexed with TCR and MHC reveals novel insights into superantigenic T cell activation.
- 2010
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 1:8
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Tidskriftsartikel (refereegranskat)abstract
- Superantigens (SAgs) are bacterial toxins that interact with immunoreceptors, T cell receptor (TCR) and major histocompatibility complex (MHC) class II, conventionally through the variable β-domain of TCR (TCRVβ). They induce a massive release of cytokines, which can lead to diseases such as food poisoning and toxic shock syndrome. In this study, we report the X-ray structure of the ternary complex between staphylococcal enterotoxin H (SEH) and its human receptors, MHC class II and TCR. The structure demonstrates that SEH predominantly interacts with the variable α-domain of TCR (TCRVα), which is supported by nuclear magnetic resonance (NMR) analyses. Furthermore, there is no contact between MHC and TCR upon complex formation. Structural analyses suggest that the major contact points to TCRVα are conserved among other bacterial SAgs. Consequently, a new dimension of SAg biology emerges, suggesting that in addition to the conventional interactions with the TCRVβ domain, SAgs can also activate T cells through the TCRVα domain.
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