Deletion of hydrophobic domains of viral glycoproteins increases the level of their production in Escherichia coli.

Overexpression of glycoprotein-encoding genes in Escherichia coli sometimes results in toxicity to the host and low protein yields. One possible explanation for this phenomenon is the presence of hydrophobic amino acid (aa) domains approx. 15-20 aa in length in the overproduced protein. As an initial test of this hypothesis, regions of hydrophobicity located within the envelope glycoproteins of HIV-1 and HTLV-1 were identified by computer analysis, and subsequently deleted by site-directed mutagenesis. The parent and modified envelope genes were expressed in bacteria using both lambda pL and T7 inducible expression systems. Removal of the hydrophobic domains reduced the apparent toxicity and significantly increased the accumulation of recombinant protein from undetectable levels to approx. 10-15% of total cellular protein.