Modifying the Lantibiotic Mutacin 1140 for Increased Yield, Activity, and Stability

Area of Science:

• Microbiology
• Biochemistry
• Drug Discovery

Background:

• Mutacin 1140 is a type AI lantibiotic with broad-spectrum activity against Gram-positive bacteria.
• Its mechanism involves binding to lipid II, inhibiting cell wall synthesis.
• Short half-life due to unprotected residues limits clinical application.

Purpose of the Study:

• To investigate the role of dehydrated and protease-susceptible residues in mutacin 1140 stability and bioactivity.
• To generate and characterize mutacin 1140 analogs with improved properties.

Main Methods:

• Site-directed mutagenesis of key residues (Dha5, Dhb14, Lys2, Arg13).
• Purification and characterization of over 15 mutacin 1140 analogs.
• Antimicrobial activity assays against Gram-positive bacteria.
• Analysis of posttranslational modifications (PTMs) and proteolytic stability.

Main Results:

• Mutacin 1140 PTM efficiency is highly dependent on the core peptide sequence.
• Specific mutations affected production, with alanine substitutions at Dha5 and Dhb14 abolishing production, while glycine substitutions restored it.
• Several analogs exhibited improved antimicrobial activity, productivity, and proteolytic stability.
• Mutations outside the lipid II binding domain interfered with target binding.

Conclusions:

• The core peptide sequence is critical for efficient mutacin 1140 PTMs and transport.
• Certain amino acid substitutions at dehydrated residue positions are tolerated and can enhance properties.
• Glutamylated core peptide analogs suggest a glutamate-dependent dehydration process.
• Developed analogs show potential for clinical applications against pathogenic bacteria due to enhanced activity and stability.