Characterization of new beta-amino acid-containing secondary métabolites in bacteria – BetaAAmetabolites

The methods and approaches used are based on those already successfully used by the project partners in a previous project funded by ANR and DFG for the isolation and structural characterization of the biosynthetic pathway of albicidin, an antibiotic and phytotoxin produced by the bacterium responsible for the sugarcane leaf scald disease.
The biosynthetic gene clusters of the two secondary metabolites studied in the current project are known. Overexpression techniques of these genes, leading to the overproduction of the secondary metabolites of interest are implemented by the French partner. The chromatographic isolation of the desired molecules is carried out jointly by the French and German partners. The structural characterization of the secondary metabolites is carried out by the German partner using various mass spectrometry and nuclear magnetic resonance techniques.
Subsequently, the respective biosynthetic pathways of these secondary metabolites are refined with respect to the structures of the molecules.
Finally, new biosynthetic gene clusters allowing the incorporation of ß-amino acids into secondary metabolites will be searched by genome mining among the bacterial genomes available on GenBank.

First results have been obtained, notably the overexpression of one of the secondary metabolites studied by a factor of 100. Concerning the other secondary metabolite, semi-purified extracts are being analyzed.

This project aims to elucidate the chemical structure of the molecules encoded by these two loci, decipher their biosynthetic pathways and refine the function of their biosynthetic genes. This project will contribute to a better understanding of ß-amino acid incorporation by autonomous A domains in bacteria. Since the targeted microorganisms are important pathogenic bacteria, this project will essentially contribute to a better understanding of their pathogenesis. Therefore, the control of these pathogenic bacteria should be facilitated by the new data from the project.
Since genome mining is an important approach to discover new loci encoding new natural products with potentially novel biological activities, this project proposes to explore the bacterial genomic sequences available in Genbank for the presence of new loci encoding an autonomous ß-amino acid specific A-domain.

No scientific production so far.

In recent years, the number of identified non-proteinogenic amino acid-containing secondary metabolites and their biosynthetic gene clusters has greatly expanded in bacteria. A new family of stand-alone adenylation (A) domains involved in the incorporation of ß-amino acids has been previously described. Based on the protein structural analyses of three members of this new family, new ß-amino acid specificity-conferring codes have been proposed. A common specific feature of these stand-alone A domains is that they are co-encoded with a stand-alone acyl carrier protein domain.
Based on these specific features, the French partner (BGPI) has identified two new stand-alone A domains expected to be involved in the incorporation of a ß-amino acid. These stand-alone A domains are present in two loci belonging to important pathogenic bacteria. According to their annotation, these loci encode two different new unknown molecules, respectively. Interestingly, by a genetic approach, these loci have both been shown to be required for the bacterial virulence. However, the chemical structure of the secondary metabolites synthesized by these loci remains unknown and the presence of a ß-amino acid has never been yet suspected and explored.
This project aims at elucidating the chemical structure of the molecules encoded by these two loci, deciphering their biosynthesis pathways, and refining the functional assignment of their biosynthesis genes. This project will contribute to a better understanding of the incorporation of ß-amino acids by stand-alone A domains in bacteria. Since the targeted microorganisms are important pathogens, this project will essentially contribute to a deeper understanding of their pathogenicity. Consequently, the fight against these pathogens should therefore be facilitated by new data arising from the project.
Since genome mining is an important approach to discover new loci encoding new natural products with potentially novel biological activities, this project proposes to mine bacterial genomic sequences available in Genbank for the presence of new loci encoding a stand-alone A domain specific of a ß amino acid.
Depending on the biological activity of the characterized ß-amino acid-containing secondary metabolites, this project potentially could lead to industrial applications as antibiotics or plant protection agents. Patents obtained would potentially also contribute to the visibility of the project. The French and German partners BGPI and TU Berlin have developed a long-standing collaboration since 2005, working together on several projects including the structural characterization of the potent antibiotic albicidin.