Heterologous production of cyanobacterial compounds

Abstract

Cyanobacteria produce a plethora of compounds with unique chemical structures and diverse biological activities. Importantly, the increasing availability of cyanobacterial genome sequences and the rapid development of bioinformatics tools have unraveled the tremendous potential of cyanobacteria in producing new natural products. However, the discovery of these compounds based on cyanobacterial genomes has progressed slowly as the majority of their corresponding biosynthetic gene clusters (BGCs) are silent. In addition, cyanobacterial strains are often slow-growing, difficult for genetic engineering, or cannot be cultivated yet, limiting the use of host genetic engineering approaches for discovery. On the other hand, genetically tractable hosts such as Escherichia coli, Actinobacteria, and yeast have been developed for the heterologous expression of cyanobacterial BGCs. More recently, there has been increased interests in developing model cyanobacterial strains as heterologous production platforms. Herein, we present recent advances in the heterologous production of cyanobacterial compounds in both cyanobacterial and non-cyanobacterial hosts. Emerging strategies for BGC assembly, host engineering, and optimization of BGC expression are included for fostering the broader applications of synthetic biology tools in the discovery of new cyanobacterial natural products.

Beyond Soil-Dwelling Actinobacteria: Fantastic Antibiotics and Where to Find Them

“…Cyanobacteria, the phylum of Gram-negative, slow-growing photosynthetic bacteria, are another prolific source of natural products. This ancient lineage of bacteria is widely distributed in nature and can be found both in marine and freshwater bodies, as well as in the soil and some extreme environments or even in symbiotic associations, such as lichens [ 232 , 233 ] or with multiple marine invertebrates, as previously discussed. From the secondary metabolism point of view, cyanobacteria are arguably the second most studied group after Actinobacteria, mainly due to their ecological impact and human health and economic implications.…”

“…More recently, filamentous cyanobacteria like Anabaena PCC 7120 and unicellular cyanobacteria with fast doubling times and good biomass production, such as Synechococcus elongatus PCC 7942 or Synechococcus sp. PCC 11901, are being explored as heterologous expression hosts [ 233 , 252 , 253 , 254 , 255 ]. In parallel, multiple genetic manipulation tools for cyanobacteria are being developed, including modular vector systems such as Synebrick for S. elongatus PCC 7942 [ 256 ] or the GoldenGate moclo-based CyanoGate system [ 257 ], CRISPR-Cas-based tools [ 258 ] as well as multiple synthetic biology elements and other techniques to optimize gene cluster expression [ 233 , 259 ].…”

“…PCC 11901, are being explored as heterologous expression hosts [ 233 , 252 , 253 , 254 , 255 ]. In parallel, multiple genetic manipulation tools for cyanobacteria are being developed, including modular vector systems such as Synebrick for S. elongatus PCC 7942 [ 256 ] or the GoldenGate moclo-based CyanoGate system [ 257 ], CRISPR-Cas-based tools [ 258 ] as well as multiple synthetic biology elements and other techniques to optimize gene cluster expression [ 233 , 259 ].…”

Fischerazoles A-C, cyanobacterial polychlorinated lipids featuring fatty acyl chain rearrangement

“…17 Despite this richness of orphan BGCs, we currently lack genetic tools to manipulate most BGC-rich cyanobacteria. 18 Therefore, BGC-guided natural product discovery in these organisms is typically restricted to leveraging structural predictions from BGC analysis 19,2020 or to the technically-challenging heterologous expression of the BGC. 18 We have recently developed a BGC-agnostic metabolomics method aimed at the discovery of cyanobacterial natural products containing fatty-acid derived moieties.…”

“…18 Therefore, BGC-guided natural product discovery in these organisms is typically restricted to leveraging structural predictions from BGC analysis 19,2020 or to the technically-challenging heterologous expression of the BGC. 18 We have recently developed a BGC-agnostic metabolomics method aimed at the discovery of cyanobacterial natural products containing fatty-acid derived moieties. 21 The method employs supplementation of cyanobacterial cultures with perdeuterated hexanoic acid.…”