Novel Selectable Marker Sesquiterpenoid Antibiotic Pentalenolactone

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Antibiotic resistance is a significant global health challenge, necessitating the discovery of novel antimicrobial compounds and their mechanisms of action.
• The phylum Actinomycetota, particularly strains from underexplored environments, are promising sources of new antibiotics.
• Competition in nutrient-limited habitats drives the production of secondary metabolites, including antibiotics, by microorganisms.

Purpose of the Study:

• To isolate and characterize novel antibiotic-producing strains from unique environments.
• To investigate the mechanism of action of pentalenolactone, an antibiotic produced by Streptomyces sp. AP22.
• To identify genetic mechanisms conferring resistance to pentalenolactone and explore its application as a selectable marker.

Main Methods:

• Isolation and identification of Streptomyces sp. AP22 from Akhshatyrsky Gorge soils.
• Phenotypic and morphological characterization of the isolated strain.
• Biochemical analysis to determine the target enzyme of pentalenolactone (glyceraldehyde-3-phosphate dehydrogenase - GAPDH).
• Genetic analysis to identify mutations in the gapA gene conferring resistance.

Main Results:

• Streptomyces sp. AP22 was identified as a producer of pentalenolactone.
• Pentalenolactone was confirmed to inhibit GAPDH, a key enzyme in glycolysis.
• A novel mutation in the gapA gene was discovered, conferring resistance to pentalenolactone.
• The identified resistance mechanism is not linked to clinically relevant antibiotics, making it suitable for a novel selectable marker.

Conclusions:

• The study identified a new antibiotic, pentalenolactone, and its target enzyme GAPDH.
• A novel gapA gene mutation provides a basis for a new selectable marker system.
• This selectable marker can facilitate genetic manipulation in strains resistant to conventional markers like kanamycin and ampicillin.
• The findings contribute to the development of tools for advancing molecular biology studies in antibiotic resistance research.