What is it about?
The study highlights how cyanobacteria take up and metabolize guanidine as a nitrogen source, how this is regulated and how a guanidine-responsive riboswitch was established as a precise tool for engineering CO₂-neutral biotechnological applications.
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Why is it important?
Cyanobacteria play a central role in global carbon and nitrogen cycles and are promising platforms for sustainable, CO₂-neutral production of chemicals, fuels, and high-value compounds. However, the metabolic regulation in these organisms is still poorly understood, limiting their biotechnological use. This study demonstrates that guanidine is a widespread nutrient for cyanobacteria and highlights its transport, enzymatic degradation and detoxification, as well as the multilayered regulation of guanidine metabolism. Accordingly, guanidine is an integral part of cyanobacterial nitrogen metabolism. Moreover, a natural guanidine-responsive riboswitch has been shown to enable tight and tunable control of heterologous genes and, as guanidine is a quite cheap inducer, allows to manage biotechnological production processes at low-costs.
Perspectives
The characterized guanidine-responsive regulatory system opens the door to designing robust, tunable expression platforms for cyanobacteria. This enables more efficient and controllable biosynthesis of chemicals, biofuels, and biopolymers in light-driven, CO₂-neutral processes. In the long term, these insights support the development of sustainable biotechnological production routes and strengthen the role of cyanobacteria as key organisms in the emerging bio-based economy.
Stephan Klähn
Helmholtz Centre for Environmental Research
Read the Original
This page is a summary of: Deciphering guanidine assimilation and riboswitch-based gene regulation in cyanobacteria for synthetic biology applications, Proceedings of the National Academy of Sciences, December 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2519335122.
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