Highlights of biosynthetic enzymes and natural products from symbiotic cyanobacteria

Covering: up to 2023 Cyanobacteria have long been known for their intriguing repertoire of natural product scaffolds, which are often distinct from other phyla. Cyanobacteria are ecologically significant organisms that form a myriad of different symbioses including with sponges and ascidians in the marine environment or with plants and fungi, in the form of lichens, in terrestrial environments. Whilst there have been several high-profile discoveries of symbiotic cyanobacterial natural products, genomic data is scarce and discovery efforts have remained limited. However, the rise of (meta-)genomic sequencing has improved these efforts, emphasized by a steep increase in publications in recent years. This highlight focuses on selected examples of symbiotic cyanobacterial-derived natural products and their biosyntheses to link chemistry with corresponding biosynthetic logic. Further highlighted are remaining gaps in knowledge for the formation of characteristic structural motifs. It is anticipated that the continued rise of (meta-)genomic next-generation sequencing of symbiontic cyanobacterial systems will lead to many exciting discoveries in the future.