Two Master Switch Regulators Trigger A40926 Biosynthesis in Nonomuraea sp. Strain ATCC 39727

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• The glycopeptide A40926, precursor to the antibiotic dalbavancin, is produced by Nonomuraea sp. strain ATCC 39727.
• Its biosynthesis is governed by the dbv gene cluster, comprising 37 protein-coding sequences involved in antibiotic production, regulation, immunity, and export.

Purpose of the Study:

• To elucidate the regulatory mechanisms controlling glycopeptide A40926 biosynthesis in Nonomuraea sp.
• To understand the industrial importance of A40926 biosynthesis regulation for dalbavancin production.
• To compare regulatory strategies with similar glycopeptides like balhimycin and teicoplanin.

Main Methods:

• Gene cluster analysis of Nonomuraea sp. strain ATCC 39727.
• Construction and analysis of independent mutations in putative regulatory genes (dbv3, dbv4, dbv6).
• Bioassays and liquid chromatography-mass spectrometry (LC-MS) for antibiotic quantification.
• Transcriptional and quantitative reverse transcription (RT)-PCR analyses to assess gene expression.

Main Results:

• Dbv3 and Dbv4 were identified as essential positive regulators for A40926 production; dbv6 inactivation had no significant effect.
• Overexpression of dbv3 resulted in increased A40926 production levels.
• Dbv4 regulates transcription of operons dbv14-dbv8 and dbv30-dbv35.
• Dbv3 controls expression of multiple monocistronic units and operons, including those involved in precursor biosynthesis, export, and tailoring reactions.

Conclusions:

• A complex regulatory model is proposed where Dbv3 and Dbv4 coordinate A40926 biosynthesis through differential regulation of gene expression.
• Dbv3 appears to control precursor biosynthesis, export, and some tailoring reactions, while Dbv4 regulates other tailoring steps and precursor biosynthesis.
• This study highlights the diverse regulatory strategies employed in glycopeptide biosynthesis and cautions against relying solely on bioinformatic analysis.