LanB

LanB refers to a family of enzymes known as lantibiotic dehydratases, encoded within lantibiotic biosynthetic gene clusters in bacteria. It is most commonly encountered in class I lantibiotics, where LanB acts together with LanA, the ribosomally produced precursor peptide, and LanC, the lanthionine cyclase, to generate mature lantibiotics.

LanB catalyzes the dehydration of serine and threonine residues in LanA, converting them into dehydroalanine and dehydrobutyrine. The dehydration typically proceeds through phosphorylation of the side chains followed by elimination of the phosphate, creating the unsaturated amino acids that can then form thioether cross-links with cysteine residues. These post-translational modifications produce the rigid, macrocyclic structures associated with lantibiotics.

LanB enzymes are found in many Gram-positive bacteria that produce lantibiotics, such as those responsible for nisin and subtilin biosynthesis. There is diversity in the sequence and domain organization of LanB proteins, and some lantibiotic systems employ alternative, bifunctional dehydratases that perform similar chemistry.

The LanB-mediated modifications are essential for the antimicrobial activity and stability of lantibiotics. Because lantibiotics target Gram-positive bacteria and can be active against resistant strains, LanB-containing pathways are of interest for natural product discovery and the bioengineering of novel antimicrobials.

See also: LanA, LanC, lantibiotics, lanthipeptides, biosynthesis.