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Biotinylated-sortase self-cleavage purification (BISOP) method for cell-free produced proteins.

ABSTRACT: BACKGROUND: Technology used for the purification of recombinant proteins is a key issue for the biochemical and structural analyses of proteins. In general, affinity tags, such as glutathione-S-transferase or six-histidines, are used to purify recombinant proteins. Since such affinity tags often interfere negatively with the structural and functional analyses of proteins, they are usually removed by treatment with proteases. Previously, Dr. H. Mao reported self-cleavage purification of a target protein by fusing the sortase protein to its N-terminal end, and subsequently obtained tag-free recombinant protein following expression in Escherichia coli. This method, however, is yet to be applied to the cell-free based protein production. RESULTS: The histidine tag-based self-cleavage method for purifying proteins produced by the wheat cell-free protein synthesis system showed high background, low recovery, and unexpected cleavage between the N-terminally fused sortase and target protein during the protein synthesis. Addition of calcium chelator BAPTA to the cell-free reaction inhibited the cleavage. In order to adapt the sortase-based purification method to the cell-free system, we next used biotin as the affinity tag. The biotinylated sortase self-cleavage purification (BISOP) method provided tag-free, highly purified proteins due to improved recovery of proteins from the resin. The N-terminal sequence analysis of the GFP produced by the BISOP method revealed that the cleavage indeed occurred at the right cleavage site. Using this method, we also successfully purified the E2 heterocomplex of USE2N and USE2v1. The c-terminal src kinase (CSK) obtained by the BISOP method showed high activity in phosphorylating the Src protein. Furthermore, we demonstrated that this method is suitable for automatically synthesizing and purifying proteins using robots. CONCLUSION: We demonstrated that the newly developed BISOP method is very useful for obtaining high quality, tag-free recombinant proteins, produced using the cell-free system, for biochemical and structural analyses.

SUBMITTER: Matsunaga S

PROVIDER: S-EPMC2901362 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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Biotinylated-sortase self-cleavage purification (BISOP) method for cell-free produced proteins.

Matsunaga Satoko S Matsuoka Kazuhiro K Shimizu Kouhei K Endo Yaeta Y Sawasaki Tatsuya T

BMC biotechnology 20100604

<h4>Background</h4>Technology used for the purification of recombinant proteins is a key issue for the biochemical and structural analyses of proteins. In general, affinity tags, such as glutathione-S-transferase or six-histidines, are used to purify recombinant proteins. Since such affinity tags often interfere negatively with the structural and functional analyses of proteins, they are usually removed by treatment with proteases. Previously, Dr. H. Mao reported self-cleavage purification of a ...[more]

PMID: 20525307

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Project description:Autoimmune diseases are a heterogeneous group of diseases characterized by immune reactions against either a major or a limited number of the bodies own autoantigens, causing inflammation and damage to tissues and organs. Thus, identification of autoantigens is an important first step to understanding autoimmune diseases. Here we demonstrate a simple screening method for identification of autoantigens reacting with patient serum antibodies by combination of an N-terminal biotinylated protein library (BPL), produced using a wheat cell-free protein production system, and a commercially available luminescence system. Optimization studies using well-characterized autoantigens showed specific interactions between N-terminal biotinylated proteins and antibody that were sensitively detected under homogeneous reaction conditions. In this optimized assay, 1 microL of the translation mixture expressing the biotinylated proteins produced significant luminescence signal by addition of diluted serum between 1:500 and 1:10 000 in 25 microL of reaction volume. For the BPL construction, 214 mouse genes, consisting of 103 well-known autoantigens and 111 genes in the mouse autoimmune susceptibility loci, and the sera of MRL/lpr mouse were used as an autoimmune model. By this screening method, 25 well-known autoantigens and 71 proteins in the loci were identified as autoantigen proteins specifically reacting with sera antibodies. Cross-referencing with the Gene Ontology Database, 26 and 38 of autoantigen proteins were predicted to have nuclear localization and identified as membrane and/or extracellular proteins. The immune reaction of six randomly selected proteins was confirmed by immunoprecipitation and/or immunoblot analyses. Interestingly, three autoantigen proteins were recognized by immunoprecipitation but not by immunoblot analysis. These results suggest that the BPL-based method could provide a simple system for screening of autoantigen proteins and would help with identification of autoantigen proteins reacting with antibodies that recognize folded proteins, rather than denatured or unfolded forms.

Project description:BackgroundRecently, some groups have reported on cell-free synthesis of functional membrane proteins (MPs) in the presence of exogenous liposomes (liposomes). Previously, we reported synthesis of a functional AtPPT1 plant phosphate transporter that was associated with liposomes during translation. However, it is unclear whether or not lipid/MP complex formation is common to all types of MPs in the wheat cell-free system.ResultsAtPPT1 was synthesized using a wheat cell-free system with or without liposomes. AtPPT1 synthesized with liposomes showed high transport activity, but the activity of AtPPT1 synthesized without liposomes was less than 10% activity of that with liposomes. To test whether co-translational association with liposomes is observed in the synthesis of other MPs, we used 40 mammalian MPs having one to 14 transmembrane domains (TMDs) and five soluble proteins as a control. The association rate of all 40 MPs into liposomes was more than 40% (mean value: 59%), while that of the five soluble proteins was less than 20% (mean value: 12%). There were no significant differences in association rate among MPs regardless of the number of TMDs and synthesis yield. These results indicate that the wheat cell-free system is a highly productive method for lipid/MP complex formation and is suitable for large-scale preparation. The liposome association of green fluorescent protein (GFP)-fusion MPs were also tested and recovered as lipid/MP complex after floatation by Accudenz density gradient ultracentrifugation (DGU). Employment of GFP-MPs revealed optimal condition for Accudenz floatation. Using the optimized Accudenz DGU condition, P2RX4/lipid complexes were partially purified and detected as a major band by Coomassie Brilliant Blue (CBB)-staining after SDS-PAGE.ConclusionFormation of lipid/AtPPT1 complex during the cell-free synthesis reaction is critical for synthesis of a functional MP. The lipid/MP complex during the translation was observed in all 40 MPs tested. At least 29 MPs, as judged by their higher productivity compared to GFP, might be suitable for a large-scale preparation. MPs synthesized by this method form lipid/MP complexes, which could be readily partially purified by Accudenz DGU. Wheat cell-free protein synthesis in the presence of liposomes will be a useful method for preparation of variety type of MPs.

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Biotinylated-sortase self-cleavage purification (BISOP) method for cell-free produced proteins.

Publications

Biotinylated-sortase self-cleavage purification (BISOP) method for cell-free produced proteins.

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