Expanding the genetic and chemical biosynthetic diversity of cyanobactin family of natural products
Year: 2020
Type: dissertation
Abstract: Natural products are small metabolites produced by living organisms with versatile chemical structures and diverse bioactivities. Bacteria are a rich but yet underexplored source of natural products. Natural product biosynthetic pathways encode a huge array of biosynthetic enzymes which can catalyze stereospecific and regiospecific modification of intermediates to produce complex natural products from simple precursors. The biosynthetic mechanisms underlying the production of natural products vary substantially. Cyanobactins are synthesized through the post-translational modification of precursor peptides and represent one of the most abundant natural product classes produced by cyanobacteria. Cyanobactins have a macrocyclic or linear structure with antimicrobial and cytotoxic bioactivities, although their ecological function is unclear. In this study, genome mining was used to catalog the genetic diversity of cyanobactin biosynthetic pathways from bacterial and archaeal genomes. Bioinformatic analysis of microbial genomes was used to identify cyanobactin biosynthetic pathways. New cyanobactin biosynthetic pathways were studied using a combination of bioinformatics, molecular biology, microbiology, biochemistry and structural chemistry. Bioinformatic predictions of cyanobactin biosynthetic gene clusters were performed based on DNA sequence data. Subsequently, candidate strains identified based on the predictions were grown in the laboratory and subjected to mass spectrometric analysis and heterologous expression. Novel cyanobactin natural products were discovered and the enzymes underpinning their biosynthesis were characterized. In the first part of the study, the muscoride biosynthetic gene cluster was described and a new muscoride variant was discovered. Two specific prenyltransferases from the muscoride biosynthetic gene cluster, which were biochemically characterized, catalyzed the regiospesific prenylation of the N- and C-termini of the linear polyoxazole muscorides. In the second part of the study, genome mining revealed a truncated cyanobactin biosynthetic gene cluster across the bacterial and archaeal domains for the production of structurally unusual cyanobactins. In the third part of the study, a regiospecific prenyltransferase was discovered, belonging to the anacyclamide cyanobactin pathway and catalyzing the N-prenylation of the tryptophan residue of the substrate peptide. The main aim of this work was to uncover novel cyanobactin biosynthetic gene clusters from bacteria and expand knowledge regarding the biosynthetic potential of cyanobactin pathways. The results from this thesis broaden the chemical diversity of the cyanobactin family and expand upon the biosynthetic logic underlying cyanobactin biosynthesis.
Source: Työväentutkimus Vuosikirja
Author: Antti Mattila
Language: English
Subfield: Applied Microbiology and Biotechnology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3111102734