AEROBIC EXPRESSION OF THE CYF GENE ENCODING CYTOCHROME C-553 FROM DESULFOVIBRIO-VULGARIS HILDENBOROUGH IN ESCHERICHIA-COLI

Monohaem cytochrome c-553 from Desulfovibrio vulgaris Hildenborough is encoded by the cyf gene which could be expressed in Escherichia coli to yield the periplasmic holoform of cytochrome c-553. Covalent haem a ttachment was shown by labelling with 5-amino4-C-14laevulinic acid, the immediate precursor for haem biosynthesis. Visible-absorption spec troscopy demonstrated that the haem environment in the recombinant pro tein did not differ from the native protein. Optimal expression was ob tained under aerobic conditions. Furthermore, efficient insertion of h aem into a cytochrome c-553-beta-lactamase fusion protein could be dem onstrated. We suggest that the varying success in heterologous express ion of c-type cytochromes in E. coli may arise as a result of differen ces in the physical properties of the apoproteins.