Protein synthesis inhibitors and ethanol selectively enhance heterologous expression of P450s and related proteins in Escherichia coli

The antibiotics chloramphenicol (Cm), tetracycline, and erythromycin, which inhibit bacterial protein synthesis and are known to induce the cold shock response, unexpectedly enhance the heterologous expression of P450s and re lated proteins in Escherichia coli. In contrast, antibiotics that mimic hea t shock in E. coli such as puromycin, streptomycin, and kanamycin decrease the expression of the same proteins. A sublethal dose of Cm (1 mu g/ml) eff ectively enhances the expression of both membrane-bound proteins (microsoma l and mitochondrial P450s) and a soluble mitochondrial protein (adrenodoxin ) over the range of two- to eightfold. The ex pression level of N-terminal truncated P450c17 (1600 nmol/liter culture without Cm), for instance, reach ed 3500 nmol/liter culture by the addition of Cm, approximately 8.4% of the total cellular protein. Cm also enabled expression at useful levels of act ive P450s previously difficult to express in E. coli. In contrast; the expr ession of P450scc, a mitochondrial protein, is decreased by Cm but enhanced by ethanol, a powerful elicitor of heat shock response in E. coli. These r esults show that both the cold shock response induced by some antibiotics a nd the heat shock response induced by ethanol may lead to enhanced expressi on of certain heterologous proteins in E. coli. This study also indicates-t hat protein synthesis inhibitors associated with the cold shock response ma y act as protein synthesis enhancers under certain conditions. (C) 1999 Aca demic Press.