Expression and membrane association of hepatitis C virus envelope 1 protein

The expression of hepatitis C virus (HCV) E1 protein is toxic for Escherich ia coli cells. For this reason, we have cloned the E1 gene in the pET3a vec tor and analyzed the inducible expression of the protein in two strains of E. coli characterised by a different level of reduction of basal synthesis. The results indicated that synthesis of E1 was supported only by the BL21( DE3)pLysS strain which provides a tightest control of protein expression be fore the induction. The BL21(DE3)pLysS cells were then used for the express ion of E1 gene, varying at its carboxy terminus in order to retain (E1, aa 192-383) or delete (E1t, aa 192-340) a C-terminal hydrophobic region that m ay be involved in membrane association. Following cell fractionation, E1 pr otein was found associated with the membrane fraction. By contrast, the tru ncated mutant E1t, was identified in the soluble phase suggesting a direct role for the C-terminal domain in E1 membrane association.