Engineering dehydro amino acids and thioethers into peptides using lacticin 481 synthetase

Area of Science:

• Biochemistry
• Synthetic Biology
• Medicinal Chemistry

Background:

• Lantibiotics are a class of peptide antimicrobials characterized by unique thioether-bridged amino acids like lanthionine (Lan) and methyllanthionine (MeLan).
• The synthetic incorporation of these modified amino acids, including dehydroalanine (Dha) and dehydrobutyrine (Dhb), into peptides is challenging, limiting their therapeutic development.
• Current in vivo production methods are restricted to peptides composed of standard proteinogenic amino acids.

Purpose of the Study:

• To investigate the enzymatic capabilities of lacticin 481 synthetase (LctM) for peptide modification.
• To explore the potential of LctM in generating novel peptide structures with thioether linkages.
• To assess the feasibility of using LctM for the synthesis of conformationally constrained peptide therapeutics.

Main Methods:

• Utilized in vitro processing of semisynthetic peptide substrates with the lacticin 481 synthetase (LctM).
• Employed a chemoenzymatic strategy involving the cyclization of peptidic substrates containing nonproteinogenic cysteine analogs.
• Analyzed the substrate tolerance and modification capabilities of LctM.

Main Results:

• Demonstrated broad substrate tolerance of LctM beyond its native prelacticin 481 peptide.
• Successfully generated novel thioether linkages by enzymatic cyclization of modified peptide substrates.
• Showcased the enzyme's ability to install dehydro amino acids and thioether rings into diverse peptide sequences.

Conclusions:

• LctM is a versatile enzyme with significant potential for engineering complex peptide structures.
• The chemoenzymatic approach using LctM offers a promising route for synthesizing conformationally constrained peptides.
• These findings pave the way for developing novel peptide-based therapeutics with enhanced stability and activity.