Figure 5.

Functional characterization of bacterial wild-type and mutant LCY-Bs. Following the identification of Glu-196 as an active-site residue of Erwinia lycopene cyclase, a plasmid-based assay was used to test wild-type and mutant Erwinia LCY-B. E. coli JM101 harboring the plasmid pACYC-EBI (chloramphenicol), which produces lycopene, was used. After transformation of E. coli JM101-pACYC-EBI (chloramphenicol) with plasmids encoding wild-type or mutant Erwinia LCY-Bs and induction with 0.5 mm isopropyl-β-thiogalactopyranoside, total carotenoids were extracted from the bacterial pellets and analyzed by HPLC as described in “Materials and Methods.” Data shown represent means ± sd for two independent experiments.