Harnessing photosynthetic ATP for whole-cell biocatalysis in the cyanobacteriumSynechocystis

Photosynthetic organisms use sunlight to produce ATP and NADPH powering their metabolism. Harnessing these products for driving biocatalytic reactions would enable to develop clean and sustainable alternatives for chemical reactions. In this study, we present the first demonstration that ATP produced from the photosynthetic process, can fuel a biocatalytic transformation in the whole-cell configuration. This result was achieved by expressing in the cyanobacteriumSynechocystissp. PCC 6803 an ATP-dependent enzyme, the γ-Glutamyl-MethylAmide Synthetase fromMethylovorus maysNo. 9 (MmGMAS). The expressed enzyme was able to drive in the transgenic strain the light-driven biosynthesis of L-theanine. Consumption of ATP by the recombinantMmGMAS was even beneficial under strong illumination, protecting the photosynthetic electron transport from photodamage. These findings demonstrate the possibility of using photosynthetic microorganisms likeSynechocystisas potential platform for sunlight driven biotransformations with wide potential biocatalytic applications. In this perspective, we further present the tridimensional structure ofMmGMAS, which explains its promiscuous in vivo activity and provides the basis for its rational evolution.