| Background. Factor VII (FVII) is a plasma glycoprotein that participates in the coagulation
process leading to the generation of fibrin. The aim of this study was to construct, express and
purify recombinant FVII fused to a polyhistidine (his) tag using Gateway technology.
Methods. To construct the entry clone, blunt-end FVII cDNA and subsequent polymerase
chain reaction (PCR) product isolated from a HepG2 cell line was TOPO-cloned into a pENTR
TOPO vector. To construct the expression clone, a LR recombination reaction was carried out
between the entry clone and destination vector, pDEST26. Chinese hamster ovary (CHO) cells
were transfected with 1 μ g of DNA of PDEST26–FVII using the FuGENE HD transfection
reagent. Two cell lines that permanently expressed recombinant FVII were established. The
expression of recombinant FVII was confirmed by reverse transcriptase PCR and enzyme-linked
immunosorbent assay. Culture medium containing his-tagged FVII was added to the nickelnitrilotriacetic
acid resin column and bound protein was eluted. The purified protein was detected
by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot
analysis. The biological activity of the recombinant FVII was determined by a prothrombin time
assay using FVII-depleted plasma.
Results. The results showed that human recombinant FVII was successfully cloned and the
accuracy of the nucleotide sequence of the gene and its frame in the vector were confirmed by
DNA sequencing. Stable clones transfected with the construct expressed FVII mRNA and related
protein but no expression was detected in the CHO cells containing an empty vector. A protein of
about 52 KDa was detected in SDS-PAGE and was further confirmed by western blot analysis.
A three-fold decrease in clotting time was observed using this recombinant FVII.
Conclusion. As far as we are aware, this is the first report of expression of recombinant FVII
fused with a his-tag through Gateway technology. The next steps, including large scale expression,
purification, activation and stabilisation, are underway. |