A SET OF BETA-GALACTOSIDASE GENE FUSION CASSETTES DEMONSTRATES USEFULNESS IN EXPRESSING HIV-1 GENES IN ESCHERICHIA-COLI

Heterologous expression in Escherichia coli is often limited by yield and solubility of the foreign protein in the bacterial cytoplasm. In m any cases, overexpression also results in growth inhibition. In order to produce retroviral proteins that are especially difficult to overex press in E. coli, we designed a set of beta-galactosidase fusion casse ttes. Fusions with beta-galactosidase increase significantly both yiel d and solubility of the foreign proteins, thus making purification muc h easier. These cassettes allow for N- or C-terminal fusions, and the retroviral proteins can be released from the fusion by automaturation in vivo for the HIV-1 protease or cleavage by thrombine for Tat. More generally, any synthetic sequence coding for a given cleavage site can be introduced 5' or 3' to the lacZ gene through a convenient set of u nique restriction sites, making these fusion cassettes highly versatil e. (C) 1994 Academic Press, Inc.