BACULOVIRUS EXPRESSION OF HUMAN BASIC FIBROBLAST GROWTH-FACTOR FROM ASYNTHETIC GENE - ROLE OF THE KOZAK CONSENSUS AND COMPARISON WITH BACTERIAL EXPRESSION

Synthetic genes encoding the 146 and 155 amino acid forms of human bas ic fibroblast growth factor (bFGF) were constructed with codon usage b iased towards the polyhedrin-encoding gene of Autographa californica n uclear polyhedrosis virus (AcNPV). Expression of both bFGF genes in Sp odoptera frugiperda (SF-21) suspension cell culture using a recombinan t baculovirus yielded similar to 2.5 mg of mitogenically fully active protein per 10(9) cells following heparin-affinity chromatography. To improve translational efficiency, the Kozak consensus sequence was int roduced and it was found that neither the replacement of a pyrimidine by a purine at position -3, nor the nature of the base at position +4 had any noticeable effect on the final levels of bFGF expression in SF -21 cells. The bases at these critical points in the consensus do not therefore play a major role in expression levels of the bFGF synthetic genes. The two synthetic genes were also expressed in Escherichia col i as native proteins using the T7 expression system. 5 mg of mitogenic ally fully active bFGF were obtained from 1 1 of bacterial culture. Bo th insect cell- and E. coli-derived bFGF were equally mitogenic for Sw iss 3T3 fibroblasts.