Engineering Chlorophyll, Bacteriochlorophyll, and Carotenoid Biosynthetic Pathways in Escherichia coli

The biosynthesis of chlorophylls (Chls) and bacteriochlorophylls(BChls) represents a key aspect of photosynthesis research. Our previouswork assembled the complete pathway for the synthesis of Chl a in Escherichia coli; herewe engineer the more complex BChl a pathway in thesame heterotrophic host. Coexpression of 18 genes enabled E. coli to produce BChl a, verifyingthat we have identified the minimum set of genes for the BChl a biosynthesis pathway. The protochlo-rophyllide reductionstep was mediated by the bchNBL genes, and this samemodule was used to modify the Chl a pathway previouslyconstructed in E. coli, eliminatingthe need for the light-dependent protochlorophyllide reductase. Furthermore,we demonstrate the feasibility of synthesizing more than one familyof photosynthetic pigments in one host by engineering E. coli strains that accumulate the carotenoids neurosporeneand & beta;-carotene in addition to BChl a.

Automated summary

In this study, the researchers successfully engineered the biosynthetic pathway of bacteriochlorophyll a (BChl a) in Escherichia coli, using coexpression of 18 genes. They identified the bchNBL genes as responsible for the protochlorophyllide reduction step and utilized the same module to modify the previously constructed pathway for chlorophyll a (Chl a) synthesis. Furthermore, they demonstrated the possibility of synthesizing multiple families of photosynthetic pigments in one host by engineering E. coli strains to produce not only BChl a but also carotenoids neurosporene and β-carotene.