A Genetic Tool to Express Long Fungal Biosynthetic Genes

Author: mycolabadmin
2023-02-01
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Summary

This research developed a new genetic tool that allows scientists to express large genes from fungi in laboratory conditions. This breakthrough enables the production of potentially valuable compounds that were previously difficult or impossible to access. The impact on everyday life includes: • Potential development of new antibiotics, particularly against tuberculosis • More sustainable production methods for industrial chemicals and materials • Access to new natural compounds that could be used in medicine or industry • Ability to study previously unculturable fungi that may produce beneficial compounds • More efficient and environmentally friendly ways to produce valuable fungal products

Background

Secondary metabolites (SMs) from mushroom-forming fungi (Basidiomycota) and early diverging fungi (EDF) such as Mucoromycota are scarcely investigated. In many cases, production of SMs is induced by unknown stress factors or is accompanied by seasonable developmental changes on fungal morphology. Moreover, many of these fungi are considered as non-culturable under laboratory conditions which impedes investigation into SM. In the post-genomic era, numerous novel SM genes have been identified especially from EDF. As most of them encode multi-module enzymes, these genes are usually long which limits cloning and heterologous expression in traditional hosts.

Objective

To develop an expression system in Aspergillus niger suitable for the production of secondary metabolites from both Basidiomycota and early diverging fungi, enabling the assembly, targeted integration and expression of genes larger than 20 kb in size in one single step.

Results

The system successfully assembled and expressed the 8 kb polyketide synthase gene lpaA from the basidiomycete Laetiporus sulphureus from five overlapping DNA fragments, producing laetiporic acids. Additionally, the uncharacterized >20 kb nonribosomal peptide synthetase gene calA from the early diverging fungus Mortierella alpina was expressed, revealing production of the antimycobacterial compound calpinactam. This represents the first report of heterologous production of a full-length SM multidomain enzyme from early diverging fungi.

Conclusion

The developed expression system allows the assembly, targeted integration and expression of genes larger than 20 kb in A. niger in one single step. The system is suitable for evolutionary distantly related secondary metabolite genes from both Basidiomycota and early diverging fungi, enabling access to new secondary metabolite resources including genetically intractable or non-culturable fungi.

Published in:Fungal Biology and Biotechnology,
Study Type:Laboratory Research,
Source: 10.1186/s40694-023-00152-3