[Construction and properties of a hybrid operon coding the HBcAG and beta-galactosidase of the hepatitis B virus in Escherichia coli].

A set of plasmids was constructed, that carries the hybrid operons with an artificial region for translation initiation of the second cistron. The SD-sequence situated close to the termination signal of the previous cistron facilitates the reinitiation of translation. Both HBcAg and beta-galactosidase coding cistrons are functionally active. The analysis of expression efficacy shows: 1) The second cistron possesses its own initiation region; ii) the opportunity of translation reinitiation increases of the protein synthesis level. The correlation between the translation initiation efficacy and the structure of the initiator codon was investigated. AUG and UUG provide comparable protein synthesis levels, AUG being 1.5-3 times more effective. Probably, there exists a different efficacy of recognition of initiator codons by ribosomes for the systems with independent and connected initiation of translation. The influence of mRNA secondary structure in the translation initiation region on expression is discussed.