Bacteriocins

Nisin is a polycyclic antibacterial peptide produced by the bacterium Lactococcus lactis that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), didehydroalanine (Dha), and didehydroaminobutyric acid (Dhb). These unusual amino acids are introduced by posttranslational modification of the precursor peptide. In these reactions a ribosomally synthesized 57-mer is converted to the final peptide. The unsaturated amino acids originate from serine and threonine, and the enzyme-catalysed addition of cysteine r

Bacteriocins are proteinaceous or peptidic toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). They are similar to yeast and paramecium killing factors, and are structurally, functionally, and ecologically diverse. Applications of bacteriocins are being tested to assess their application as narrow-spectrum antibiotics.

A colicin is a type of bacteriocin produced by and toxic to some strains of Escherichia coli. Colicins are released into the environment to reduce competition from other bacterial strains. Colicins bind to outer membrane receptors, using them to translocate to the cytoplasm or cytoplasmic membrane, where they exert their cytotoxic effect, including depolarisation of the cytoplasmic membrane, DNase activity, RNase activity, or inhibition of murein synthesis.

Reuterin (3-hydroxypropionaldehyde) is the organic compound with the formula HOCH2CH2CHO. It is a bifunctional molecule, containing both a hydroxy and aldehyde functional groups.

thumb | right Lysostaphin (, glycyl-glycine endopeptidase) is a Staphylococcus simulans metalloendopeptidase (crystal structure of lysostaphin). It can function as a bacteriocin (antimicrobial) against Staphylococcus aureus.