Elsevier, Protein Expression and Purification, 1(28), p. 173-181, 2003
DOI: 10.1016/s1046-5928(02)00681-2
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The third domain of the periplasmic protein TolA from Escherichia coli (TolAIII) was used as a fusion partner in the expression of various proteins from bacteria and eukaryotes. TolAIII is small domain, expressed in high yields as a soluble protein in the cytoplasm of E. coli. Proteins were linked to the C-terminus of TolAIII by a short flexible linker containing sites for endopeptidases. Three different vectors were prepared, containing sites for enterokinase, thrombin or factor Xa. Fusion proteins also contain a His(6)-Ser(2) tag at their N-terminus for easier purification. Up to 90 mg fusion protein per liter bacterial culture was obtained using these vectors. Colicin N R-domain was expressed with this system as a fusion and processed further for functional studies. The yield of final pure R-domain was doubled as compared to the direct expression. The system may prove to be useful in the preparation of other peptides and proteins.