Lantibiotics

Lantibiotics are a class of peptide antibiotics that contain the unusual amino acid lanthionine. They are produced by Gram-positive bacteria and have a broad spectrum of activity against other Gram-positive bacteria, including many that are pathogenic to humans.

Structure and Biosynthesis

Lantibiotics are characterized by the presence of lanthionine, a sulfur-containing amino acid that is formed by a post-translational modification of serine or cysteine residues. This modification involves the dehydration of serine or cysteine to dehydroalanine or dehydrobutyrine, respectively, followed by a Michael addition of a cysteine thiol to the dehydrated residue.

The biosynthesis of lantibiotics is a complex process that involves multiple enzymes and steps. The lantibiotic precursor peptide, known as a LanA peptide, is synthesized by the ribosome and then modified by a series of enzymes to form the mature lantibiotic.

Mechanism of Action

Lantibiotics exert their antibacterial activity by binding to the cell membrane of target bacteria and forming pores, which leads to cell death. Some lantibiotics, such as nisin, also inhibit cell wall synthesis by binding to lipid II, a key intermediate in the cell wall biosynthesis pathway.

Clinical Use and Resistance

Lantibiotics have potential for clinical use due to their potent antibacterial activity and low toxicity to human cells. However, their use is currently limited by the development of resistance in target bacteria. Resistance mechanisms include modification of the cell membrane to reduce lantibiotic binding, and production of enzymes that degrade lantibiotics.

Examples

Examples of lantibiotics include nisin, subtilin, and mersacidin. Nisin is used as a food preservative, while subtilin and mersacidin have potential for clinical use due to their potent antibacterial activity.

See Also

• Antibiotics
• Peptide antibiotics
• Gram-positive bacteria