Lantibiotics - Citizendia

Lantibiotics are a class of peptide antibiotics that contain polycyclic thioether amino acids as well as the unsaturated amino acids dehydroalanine and 2-aminoisobutyric acid. Peptides (from the Greek πεπτίδια, "small digestibles" are short Polymers formed from the linking in a defined order of α- Amino In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa A thioether (similar to Sulfide) is a functional group in Organic chemistry that has the structure R1-S-R2 as shown on right In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this In Chemistry, saturation has five different meanings In Physical chemistry, saturation is the point at which a Solution of a substance Dehydroalanine (or (alpha-(beta-di-dehydroalanine) is an uncommon Amino acid found in Peptides of microbial origin (an unsaturated 2-Aminoisobutyric acid, or α-aminoisobutyric acid ( AIB) or α-methylalanine or 2-methylalanine, is an Amino acid with the Structural These characteristic cyclic thioether amino acids are composed of either lanthionine or methyllanthionine. Lanthionine is a Nonproteinogenic Amino acid with the chemical formula (HOOC-CH(NH2-CH2-S-CH2-CH(NH2-COOH Lantibiotics are produced by a large number of Gram positive bacteria such as Streptococcus and Streptomyces to attack other gram positive bacteria and as such they are considered a member of the bacteriocins. Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. Streptococcus is a Genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the Streptomyces, the largest Genus of Actinobacteria and type genus of the family Streptomycetaceae. Bacteriocins are Proteinaceous Toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s

Lantibiotics are well studied because of the commercial use of these bacteria in the food industry for making dairy products such as cheese. Cheese is a Food made from Milk, usually the milk of cows, Buffalo, Goats or sheep, by coagulation. Bacteriocins are classified according to their extent of posttranslational modification. Posttranslational modification (PTM is the chemical modification of a Protein after its translation. The lantibiotics are a class of more extensively modified bacteriocins, also called Class I. Bacteriocins for which disulfide bonds are the only modification to the peptide are Class II bacteriocins. In Chemistry, a disulfide bond is a single Covalent bond derived from the coupling of Thiol groups Most bacteriocins are biologically active single-chain peptides. Some are only active as partners with a second peptide (see Class IIb, below).

Nisin and epidermin are members of a family of lantibiotics that bind to a cell wall precursor lipid component of target bacteria and disrupt cell wall production. Nisin is a polycyclic Peptide antibacterial with 34 Amino acid residues used as a food Preservative. A cell wall is a tough flexible and sometimes fairly rigid layer surrounding a cell, located external to the Cell membrane, which provides the cell with structural The duramycin family of lantibiotics binds phosphoethanolamine in the membranes of its target cells and seem to disrupt several physiological functions. Lantibiotics are a class of Peptide Antibiotics that contain polycyclic Thioether Amino acids as well as the unsaturated amino acids Phosphorylethanolamine is an Ethanolamine derivative that is used to construct Sphingomyelins Additional images The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer

1 History
2 Classification
3 Biosynthesis
4 Mechanism of action
5 Application
6 References
7 External links

History

^[1]The name Lantibiotics was introduced in 1988 as an abbreviation for "Lanthionine-containing peptide antibiotics". In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa The first structures of these antimicrobial agents were produced by pioneering work by Gross and Morell in the late sixties and early seventies, thus marking the formal introduction of Lantibiotics. An antimicrobial is a substance that kills or inhibits the growth of Microbes such as Bacteria, Fungi, or Viruses. Since then Lantibiotics such as Nisin have been used auspiciously for food preservation and have yet to encounter significant bacterial resistance. Nisin is a polycyclic Peptide antibacterial with 34 Amino acid residues used as a food Preservative. These attributes of lantibiotics have led to more detailed research into their structures and biosynthetic pathways. Biosynthesis is a phenomenon wherein Chemical compounds are produced from simpler Reagents Biosynthesis unlike Chemosynthesis, takes place within living

Classification

Type A Lantibiotics are long flexible molecules - eg Nisin, subtilin, epidermin. Nisin is a polycyclic Peptide antibacterial with 34 Amino acid residues used as a food Preservative. Subgroup AI includes Mutacin II, subgroup AII includes Mutacin I & III.
Type B Lantibiotics are globular - eg mersacidin, actagardine, cinnamycin.

Biosynthesis

The biosynthesis is interesting <details to be added>. They are synthesised with a leader polypeptide sequence which is only removed during the transport of the molecule out of the synthesising cell.

Mechanism of action

Lantibiotics show substantial specificity for some components (eg lipid II) of bacterial cell membranes especially of Gram positive bacteria. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Type A kill rapidly by pore formation, type B inhibit peptidoglycan biosynthesis. See Brotz and Sahl. JAC (2000) 46, 1-6 for discussion of mechanism of action. They are active in very low concentrations.

Application

^[2]Lantibiotics are produced by Gram-positive bacteria and show strong antimicrobial action towards a wide range of other Gram-positive bacteria. As such they have become attractive candidates for use in food preservation (by inhibiting pathogens that cause food spoilage) and the pharmaceutical industry (to prevent or fight infections in humans or animals). Food preservation is the process of treating and handling Food in a way that preserves its edibility and nutrition value Enzyme inhibitors are Molecules that bind to Enzymes and decrease their activity. A pathogen (from Greek πάθος pathos "suffering passion" and γἰγνομαι (γεν- gignomai (gen- "I give birth to" infectious See C. van Kraaij et al, Nat. Prod. Rep. (1999), 16, 583 - 584 for more detailed disccusion of the pharmaceutical application of lantibiotics.

References

^ [1]
^ [2]

1. W. van der Donk et al. Chem. Rev. (2005) 105, 633 - 683
2. C. van Kraaij et al, Nat. Prod. Rep. (1999), 16, 575 - 587.

External links

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