REDUCTION OF GROWTH AND ACETYL-COA CARBOXYLASE ACTIVITY BY EXPRESSIONOF A CHIMERIC STREPTAVIDIN GENE IN ESCHERICHIA-COLI

The streptavidin gene from Streptomyces avidinii was expressed in E. c oli as a non-fusion protein and as a glutathione S-transferase fusion protein. The streptavidin protein accumulated primarily in the inclusi on bodies and did not alter cell growth. In contrast, the glutathione- S-transferase-streptavidin fusion protein was soluble. Nondenaturing p olyacrylamide gel electrophoresis indicated that the chimeric glutathi one-S-transferase-streptavidin protein was present mostly as a monomer , with some detectable polymeric forms. Cells grown in the presence of [H-3]-biotin had label specifically associated with the expressed glu tathione-S-transferase-streptavidin fusion protein, indicating this pr otein bound biotin in vivo. The majority of the radiolabeled biotin wa s associated with polymeric forms of the glutathione-S-transferase-str eptavidin protein. The growth rates of biotin auxotrophs of E. coli gr owing in biotin-deficient media were substantially decreased by the ex pression of the glutathione-S-transferase-streptavidin gene. The decre ased growth rate correlated with a decrease in acetyl-CoA carboxylase activity.