One-step affinity purification of bacterially produced proteins by means of the “Strep tag” and immobilized recombinant core streptavidin (original) (raw)
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Protein Engineering Design and Selection, 1997
The Strep-tag, an artificial peptide ligand of streptavidin, has gained use as an affinity handle for the purification and detection of recombinant fusion proteins. In an attempt to achieve tighter complexation of the peptide, streptavidin was engineered and the amino acid residues 44-47 in the flexible loop from 44 to 53, which is close to the binding site, were subjected to random mutagenesis. A fusion between alkaline phosphatase and the Strep-tag II sequence, an improved version of the Strep-tag, was constructed as a molecular probe for peptide binding. By means of a filter-sandwich assay, two streptavidin mutants with significantly stronger binding activity for the Strep-tag II were thus identified from a library of Escherichia coli colonies. Both in an ELISA with the alkaline phosphatase fusion and in a fluorescence titration experiment with the synthetic Strep-tag II peptide, which carried an anthraniloyl group as chromophore, their affinities were found to be higher by more than one order of magnitude compared with wild-type streptavidin. The nature of the amino acid exchanges and an enhanced electrophoretic mobility of the streptavidin tetramers suggest an altered loop conformation to be part of the optimized binding mechanism. When one of the streptavidin mutants was immobilized on a chromatographic column it exhibited clearly improved performance in the purification of Strep-tag II fusion proteins, and desthiobiotin turned out to be a suitable reagent for mild competitive elution.
Applications of a peptide ligand for streptavidin: the Strep-tag
Biomolecular Engineering, 1999
The Strep-tag constitutes a nine amino acid-peptide that binds specifically to streptavidin and occupies the same pocket where biotin is normally complexed. Since the Strep-tag participates in a reversible interaction it can be applied for the efficient purification of corresponding fusion proteins on affinity columns with immobilized streptavidin. Elution of the bound recombinant protein can be effected under mild buffer conditions by competition with biotin or a suitable derivative. In addition, Strep-tag fusion proteins can be easily detected in immunochemical assays, like Western blots or ELISAs, by means of commercially available streptavidin-enzyme conjugates. The Strep-tag/streptavidin system has been systematically optimized over the past years, including the engineering of streptavidin itself. Structural insight into the molecular mimicry between the peptide and biotin was furthermore gained from X-ray crystallographic analysis. As a result the system provides a reliable and versatile tool in recombinant protein chemistry. Exemplary applications of the Strep-tag are discussed in this review.
Protein Expression and Purification, 2001
Protein affinity tags are widely used for the purifica-We describe the use of the SBP-tag, a new streptavition and detection of recombinant proteins, particularly din-binding peptide, for both the one-step purification from complex mixtures such as lysed cells. However, and the detection of recombinant proteins. The SBPonly a small number of affinity tags are available, and tag sequence is 38 amino acids long and binds to strepthere are significant drawbacks associated with the use tavidin with an equilibrium dissociation constant of of many of them. Commonly used categories of tags, 2.5 nM. We demonstrate that a single-step purification and their limitations, are described below: of SBP-tagged proteins from bacterial extract yields samples that are more pure than those purified using maltose-binding protein or the His-tag. The capacity
Protein Expression and Purification, 2002
To expand the application of the streptavidin-biotin technology for reversible affinity purification of biotinylated proteins, a novel form of monomeric streptavidin was engineered and produced using Bacillus subtilis as the expression host. By changing as little as two amino acid residues (T90 and D128) to alanine, the resulting mutant streptavidin designated DM3 was produced 100% in the monomeric form as a soluble functional protein via secretion. It remained in the monomeric state in the presence or absence of biotin. Interaction of purified monomeric streptavidin with biotin was studied by surface plasmon resonance-based BIAcore biosensor. Its on-rate is comparable to that of monomeric avidin while its off-rate is seven times lower. The dissociation constant was determined to be 1:3 Â 10 À8 M. These properties make it an attractive agent for affinity purification of biotinylated proteins. An affinity matrix with immobilized DM3 mutein was prepared and applied to purify biotinylated cytochrome c from a crude extract. Biotinylated cytochrome c could be purified to homogeneity in one step and was shown to retain full biological activity. Advantages of using DM3 mutein over other traditional methods in the purification of biotinylated proteins are discussed.
Expression and purification of soluble monomeric streptavidin in Escherichia coli
We recently reported the engineering of monomeric streptavidin (mSA) for use in monomeric detection of biotinylated ligands. Although mSA can be expressed functionally on the surface of mammalian cells and yeast, the molecule does not fold correctly when expressed in Escherichia coli. Refolding from inclusion bodies is cumbersome and yields a limited amount of purified protein. Improving the final yield should facilitate its use in biotechnology. We tested the expression and purification of mSA fused to GST, MBP, thioredoxin, and sumo tags to simplify its purification and improve the yield. The fusion proteins can be expressed solubly in E. coli and increase the yield by more than 20fold. Unmodified mSA can be obtained by proteolytically removing the fusion tag. Purified mSA can be immobilized on a solid matrix to purify biotinylated ligands. Together, expressing mSA as a fusion with a solubilization tag vastly simplifies its preparation and increases its usability in biotechnology.
Reports of biochemistry & molecular biology, 2018
Background Streptavidin is a protein produced by Streptomyces avidinii with strong biotin-binding ability. The non-covalent, yet strong bond between these two molecules has made it a preferable option in biological detection systems. Due to its extensive use, considerable attention is focused on streptavidin production by recombinant methods. Methods In this study, streptavidin was expressed in Escherichia coli (E. coli) BL21 (DE3) pLysS cells and purified by affinity chromatography. Various dialysis methods were employed to enable the protein to refold to its natural form and create a strong bond with biotin. Results Streptavidin was efficiently expressed in E. coli. Streptavidin attained its natural form during the dialysis phase and the refolded protein bound biotin. The addition of proline or arginine to the dialysis buffer resulted in a refolded streptavidin with greater affinity for biotin than refolding in dialysis buffer with no added amino acids. Conclusion Dialysis of reco...
"Protein Engineering, Design and Selection", 1996
In antigen-antibody interactions, the high avidity of antibodies depends on the affinity and number of the individual binding sites. To develop artificial antibodies with multiple valency, we have fused the single-chain antibody Fv fragments to core streptavidin. The resulting fusion protein, termed scFv::strep, was found after expression in Escherichia coli in periplasmic inclusion bodies. After purification of the recombinant product by immobilized metal affinity chromatography, refolding and size-exclusion FPLC, tetrameric complexes resembling those of mature streptavidin were formed. The purified tetrameric scFv::strep complexes demonstrated both antigen-and biotin-binding activity, were stable over a wide range of pH and did not dissociate at high temperatures (up to 70°C). Surface plasmon resonance measurements in a BIAIite system showed that the pure scFv::strep tetramers bound immobilized antigen very tightly and no dissociation was measurable. The association rate constant for scFv::strep tetramers was higher than those for scFv monomers and dimers. This was also reflected in the apparent constants, which was found to be 35 times higher for pure scFv::strep tetramers than monomeric singlechain antibodies. We could also show that most of biotin binding sites were accessible and not blocked by biotinylated E.coli proteins or free biotin from the medium. These sites should therefore facilitate the construction of bispecific multivalent antibodies by the addition of biotinylated ligands.
Bioconjugate Chemistry, 1998
In this investigation, a comparison of wild type recombinant streptavidin (r-SAv) with two genetically engineered mutant r-SAv proteins was undertaken. The investigation also included a comparison of the r-SAv with two streptavidin (SAv) proteins from commercial sources. In vitro characterization of the SAv proteins was conducted by HPLC, SDS-PAGE, IEF, and electrospray mass spectral analyses. All SAv proteins studied appeared to be a single species by size exclusion chromatography (HPLC) and SDS-PAGE analyses, but multiple species were noted in the IEF and MS analyses. In vivo comparisons of the SAv proteins were accomplished with dual isotope-labeled SAv in athymic mice. In an initial experiment, tissue localization of r-[ 131 I]SAv directly radiolabeled using chloramine-T was compared with r-SAv radiolabeled with the N-hydroxysuccinimidyl p-iodobenzoate conjugate ([ 125 I]-PIB), a radioiodination reagent that has been shown to result in iodine-labeled proteins which are stable to in vivo deiodination. The data obtained indicated that there is little difference in the distribution (except kidney localization) when r-SAv labeled by the two methods. Data obtained from comparison of r-[ 131 I]SAv with a disulfide-stabilized r-SAv mutant (r-SAv-H127C), a C-terminal cysteine-containing r-SAv mutant (r-[ 125 I]SAv-S139C), and two 125 I-labeled SAv proteins obtained from commercial sources indicated that their distributions were quite similar, except the kidney concentrations were generally lower than that of r-[ 131 I]SAv. On the basis of the similar distributions of the SAv proteins studied, it appears that the r-SAv mutants may be interchanged for the (wild type) r-SAv in pretargeting studies. Further, the similarity of distributions with two commercially available SAv proteins suggests that the results obtained in our studies and those of other groups may be directly compared (with consideration of animal model, sacrifice time, etc.).