TRANSLATIONAL REGULATION OF A RECOMBINANT OPERON CONTAINING HUMAN PLATELET-DERIVED GROWTH-FACTOR (PDGF)-ENCODING GENES IN ESCHERICHIA-COLI - GENETIC TITRATION OF THE PEPTIDE CHAINS OF THE HETERODIMER AB

A new strategy is described for the production of recombinant heteromu ltimeric proteins using Escherichia coli as host. A recombinant operon was constructed containing modified cDNA sequences encoding the matur e A and B chains of human platelet-derived growth factor (PDGF). The r elative expression rates of the PDGF genes were varied over a range eq uivalent to A:B ratios from 0.8 to 3.7 by means of translational regul ation. This was achieved using two different translational initiation sequences (TIS) upstream from the respective coding regions, one deriv ed from the E. coli atpE translational initiation region, and the othe r containing a sequence with extended complementarity to the 3' end of the 16S rRNA. The generation of mature PDGF A and B chains in differe nt relative amounts in E. coli provided the basis for developing a nov el procedure for the production of the biologically active PDGF hetero dimer AB in large quantities. The general strategy is applicable to th e preparation of a wide range of heteromultimeric complexes. Moreover, the described PDGF operon constitutes a compact and versatile model s ystem for studies of the posttranscriptional regulation of gene expres sion.