DEVELOPMENT OF DNA ARRAY BY MICROORGANISM AND PRODUCT

摘要

Microbial expression of an exogenous polypeptide may be inefficient if the messenger RNA has secondary structure (due to complementarity of spaced regions of the molecule) which impedes interaction with a ribosome. The occurrence of such structure can be predicted. The degeneracy of the genetic code gives freedom to alter the nucleic acid composition of the cDNA to eliminate harmful secondary structure of the mRNA. For example, bovine growth hormone (BGH) is poorly expressed by E. coli transformed with a recombinant plasmid containing the natural BGH gene. The corresponding mRNA has complementary regions at 46-51 and 73-78. Therefore a plasmid pBGH 33-4 was constructed containing a BGH gene whose upstream portion was synthesized (making use of plasmid pHGH 207-1 which contains an efficiently expressible gene for the closely related human growth hormone) so as not to cause the troublesome complementarity. E. coli transformed therewith produced BGH with a yield of better than 10<5> copies per cell.