Question

The bacteriocin that is coming under 'lanthionine containing peptides'is

• A. Nisin
• B. Lacticin F
• C. Lactococcin A
• D. Helveticin

Hint:

Bacteriocins containing lanthionine are termed "lantibiotics". Nisin is the premier example of this class and is widely used as a natural preservative in the dairy and food industries.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria to inhibit the growth of closely related bacterial strains.
They are classified into different groups based on their structural characteristics, molecular weight, and post-translational modifications.
Class I bacteriocins, also known as lantibiotics, are small peptides that contain unusual sulfur-containing amino acids such as lanthionine and $\beta$-methyllanthionine.

Step 2: Detailed Explanation:
Lantibiotics are synthesized as precursor peptides that undergo extensive post-translational modifications.
Dehydration of serine and threonine residues yields dehydroalanine and dehydrobutyrine, which then react with cysteine residues to form intramolecular thioether rings.
These rings are composed of lanthionine (Lan) and $\beta$-methyllanthionine (MeLan).
Nisin, produced by certain strains of Lactococcus lactis subsp. lactis, is the most well-characterized lantibiotic and contains five of these lanthionine rings.
These rings stabilize the peptide structure, allowing Nisin to bind specifically to lipid II in the target bacterial cell wall and form pores in the cytoplasmic membrane, leading to cell death.
Lacticin F and Lactococcin A are Class II bacteriocins, which are non-modified, heat-stable, linear peptides.
Helveticin is a Class III bacteriocin, which consists of large, heat-labile proteins.
Therefore, Nisin is the correct choice as a lanthionine-containing peptide.

Step 3: Final Answer
Nisin is the lanthionine-containing bacteriocin (lantibiotic) among the options provided.