Construction and characterization of a functional variant hFGF7 with
enhanced properties by circular permutation
Abstract
Human fibroblast growth factor 7 (hFGF7) is a member of the
paracrine-acting FGF family and mediates various reactions such as wound
healing, tissue homeostasis, and liver regeneration. These activities
make it a plausible candidate for pharmaceutical applications as a drug.
However, the low expression level and stability of the recombinant hFGF7
were known to be major hurdles for further applications. Here, we
attempted to improve the expression level and stability of hFGF7 by
changing the order of amino acids through circular permutation (CP),
thereby expecting an alternative fate according to N-end rules. CP-hFGF7
variants were constructed systematically by using putative amino acid
residues in the loop region that avoided the disruption of the
structural integrity especially in the functional motif. Among them,
cp-hFGF7115-114 revealed a relatively higher
expression level in the soluble fraction than the wild-type hFGF7 and
was efficiently purified to apparent homogeneity by three consecutive
steps. Approximately, 7 mg of the purified protein was obtained from a 1
L culture and showed a comparable activity to that of the wild type
hFGF7. In addition, the spectral properties related to the apparent
structure of cp-hFGF7115-114 were quite similar to
those of the wild type hFGF7. Therefore, CP could be an alternative tool
for the functional expression of hFGF7 in Escherichia coli.