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- Woestenenk, Esmeralda A., et al.
(författare)
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His tag effect on solubility of human proteins produced in Escherichia coli: a comparison between four expression vectors.
- 2004
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Ingår i: Journal of structural and functional genomics. - 1345-711X .- 1570-0267. ; 5:3, s. 217-29
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Tidskriftsartikel (refereegranskat)abstract
- We have compared four different vectors for expression of proteins with N- or C-terminal hexahistidine (His6) tags in Escherichia coli by testing these on 20 human proteins. We looked at a total recombinant protein production levels per gram dry cell weight, solubility of the target proteins, and yield of soluble and total protein when purified by immobilized metal ion affinity purification. It was found that, in general, both N- and C-terminal His6 tags have a noticeable negative affect on protein solubility, but the effect is target protein specific. A solubilizing fusion tag was able to partly counteract this negative effect. Most target proteins could be purified under denaturing conditions and about half of the proteins could be purified under physiological conditions. The highest protein production levels and yield of purified protein were obtained from a construct with C-terminal His tag. We also observe a large variation in cell growth rate, which we determined to be partly caused by the expression vectors and partly by the targets. This variation was found to be independent of the production level, solubility and tertiary structure content of the target proteins.
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- Woestenenk, Esmeralda A., 1975-
(författare)
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Protein production, characterization and structure determination in structural genomics
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers the process from expression of a heterologous gene in Escherichia coli to structure determination of a protein by nuclear magnetic resonance (NMR) spectroscopy. The first part concerns structural genomics-related parallel screening studies on the effect of fusion tags (in particular the His tag) on protein solubility and the use of fusion tags in fast, parallel purification protocols intended for initial biophysical characterization of human proteins produced in E. coli. It was found that for most proteins the His tag has a negative influence on protein solubility. This influence appears to be more pronounced for our C-terminal His tag than for the N-terminal His tags used in this study. Moreover, high ratios of soluble per total protein do not always guarantee a high yield of soluble protein after purification, as different vector - target protein combinations result in large differences in host cell growth rates. Protein purification protocols for different fusion tags were developed that make it possible to express, purify and study structural properties of low concentration samples of 15N-labeled proteins in one or two days. The second part of this thesis describes the assignment and solution structure determination of ribosomal protein L18 of Thermus thermophilus. The protein is a mixed α/β structure with two α-helices on one side of a four-stranded β-sheet. Comparison to RNA-bound L18 showed that the protein to a large extent adopts identical structures in free and bound states, with exception of the loop regions and the flexible N-terminus. Keywords: protein production, protein solubility, fusion tags, nuclear magnetic resonance, structure determination, ribosomal protein
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| 4. |
- Woestenenk, Esmeralda A., et al.
(författare)
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The solution structure of ribosomal protein L18 from Thermus thermophilus reveals a conserved RNA-binding fold
- 2002
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 363:3, s. 553-561
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Tidskriftsartikel (refereegranskat)abstract
- We have determined the solution structure of ribosomal protein L18 from Thermus thermophilus. L18 is a 12.5 kDa protein of the large subunit of the ribosome and binds to both 5 S and 23 S rRNA. In the uncomplexed state L18 folds to a mixed α/β globular structure with a long disordered N-terminal region. We compared our high-resolution structure with RNA-complexed L 18 from Haloarcula marismortui and T. thermophilus to examine RNA-induced as well as species-dependent structural differences. We also identified T. thermophilus S11 as a structural homologue and found that the structures of the RNA-recognition sites are conserved. Important features, for instance a bulge in the RNA-contacting β-sheet, are conserved in both proteins. We suggest that the L18 fold recognizes a specific RNA motif and that the resulting RNA-protein-recognition module is tolerant to variations in sequence.
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