Abstract
Bacteriorhodopshin (BR) is an intrinsic membrane protein composed of seven membrane-spanning helices (A-G). Partial genes of bacterioopsin (BOP) which encode the peptides including ABCD helices and EFG helices of bacteriorhodopsin were independently expressed in Escherichia coli (E. coli ). Six inducible expression vectors were constructed, three of which contain a partial gene coding the ABCD helices of BOP (vectors pUBOAIN, pKBOAIN and pTKBOAIN), and three coding the EFG helices of BOP (vectors pUBOAIC, pKBOAIC and pTKBOAIC). The vectors pUBOAIN and pUBOAIC contain lac-promoter and the vectors pKBOAIN and pKBOAIC contain tac-promoter followed by the partial genes of BR. The vectors pTKBOAIN and pTKBOAIC contain a nucleotide fragment encoding the presequence of the manganese-stabilization protein of Anacystis nidurans between the lac-promoter and the BR partial gene. The expression of the resulting fusion proteins were detected by ELISA using mouse anti-BR serum. The fusion proteins prepared from F. coli transformed by pTKBOAIN or pTKBOAIC were estimated to comprise more than 1% of the total membrane protein in the E. coli.
