HaloTag is an effective expression and solubilisation fusion partner for a range of fibroblast growth factors
- Published
- Accepted
- Subject Areas
- Biochemistry
- Keywords
- Fibroblast growth factor, recombinant protein expression, HaloTag, fusion protein
- Copyright
- © 2014 Sun et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- 2014. HaloTag is an effective expression and solubilisation fusion partner for a range of fibroblast growth factors. PeerJ PrePrints 2:e743v1 https://doi.org/10.7287/peerj.preprints.743v1
Abstract
The production of recombinant proteins such as the fibroblast growth factors (FGFs) is the key to establishing their function in cell communication. The production of recombinant FGFs in E. coli is limited, however, due to expression and solubility problems. HaloTag has been used as a fusion protein to introduce a genetically-encoded means for chemical conjugation of probes. We have expressed 11 FGF proteins with an N-terminal HaloTag, followed by a tobacco etch virus (TEV) protease cleavage site to allow release of the FGF protein. These were purified by heparin-affinity chromatography, and in some instances by further ion-exchange chromatography. It was found that HaloTag did not adversely affect the expression of FGF1 and FGF10, both of which expressed well as soluble proteins. The N-terminal HaloTag fusion was found to enhance the expression and yield of FGF2, FGF3 and FGF7. Moreover, whereas FGF6, FGF8, FGF16, FGF17, FGF20 and FGF22 were only expressed as insoluble proteins, their N-terminal HaloTag fusion counterparts (Halo-FGFs) were soluble, and could be successfully purified. However, cleavage of Halo-FGF6, -FGF8 and -FGF22 with TEV resulted in aggregation of the FGF protein. Thus, HaloTag provides a means to enhance the expression of soluble recombinant proteins, in addition to providing a chemical genetics route for covalent tagging of proteins.
Author Comment
While producing an N-terminal HaloTag fusion of FGF-2, we observed increased levels of expression in E. Coli. This led us to investigate whether HaloTag may be a useful solubilisation and expression fusion partner for the production of recombinant FGFs in E. coli. Ten further FGFs were produced as HaloTag fusions. A number of these had not been documented to express as soluble proteins before. The results show clearly that HaloTag is indeed an effective expression and solubilisation partner for FGFs. Since HaloTag also provides a means to specifically label the fusion protein, it is likely to be generally useful with proteins that are difficult to express.