# Harnessing Photosynthetic ATP for Whole-Cell Biocatalysis in the Cyanobacterium Synechocystis

## TL;DR

Scientists used sunlight-powered ATP in cyanobacteria to drive a biocatalytic reaction, creating a sustainable way to produce chemicals.

## Contribution

Demonstrated that photosynthetic ATP can fuel whole-cell biocatalysis in Synechocystis using an ATP-dependent enzyme.

## Key findings

- Expressing MmGMAS in Synechocystis enabled light-driven biosynthesis of l-theanine.
- ATP consumption by MmGMAS protected the photosynthetic electron transport under strong light.
- The 3D structure of MmGMAS explains its in vivo activity and supports future enzyme evolution.

## Abstract

Photosynthetic organisms use sunlight to produce ATP
and NADPH
powering their metabolism. Harnessing these products for driving biocatalytic
reactions would enable development of clean and sustainable alternatives
for chemical reactions. In this study, we present the 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 cyanobacterium Synechocystis sp. PCC 6803 an ATP-dependent enzyme, the γ-glutamyl-methylamide
synthetase from Methylovorus mays No. 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 recombinant MmGMAS was
even beneficial under strong illumination, protecting the photosynthetic
electron transport from photodamage. These findings demonstrate the
possibility of using photosynthetic microorganisms like Synechocystis as a potential platform for sunlight driven biotransformations with
wide potential biocatalytic applications. In this perspective, we
further present the tridimensional structure of MmGMAS, which explains its promiscuous in vivo activity
and provides the basis for its rational evolution.