Lantibiotics Class I

Lantibiotics are small, membrane-active peptides ( 5 kDa) containing the unusual amino acids lanthionine, P-methyl-lanthionine, and the dehydrated residues dehydro alanine and dehydrobutyrine e.g. nisin, lacticin 481, carnocin U-149, lactocin S, sublancin 168 [29-38]. The intrachain positioning of these polycyclic structures of the lantibiotics has been used to group them into linear (Group lA) or circular (Group IB) lantibiotics [39]. Based on similarities in the 

Heat-Stable, Non-Lanthlonine Containing, Uembrane-Active Peptides (Class II) 

Class (II A) Listeria-active peptides. They have a consensus sequence in the N-terminus of-T-G-N-G-V-X-C- represented by pediocin PA-1. Other examples are sakacin A, sakacin P, leucocin A, mesentericin Y105 [42-45]. 

Class (MB) Poration complexes consisting of two proteinaceous peptides. These two peptides are necessary for full activity examples are lactococcin G, lactococcin M, lactacin F and two-component peptide systems found in the operon located in the plantaricin A gene cluster [46-49]. 

Class (IIC) Small, heat-stable, and non-modified bacteriocins translated with sec-dependent leaders. Only two reports have been made up to now divergicin A and acidocin B [50, 51]. 

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Most antimicrobial peptides produced by Gram-positive bacteria are classified as bacteriocins, and like microcins they are diverse in size and structure.35 36 Recent classification schemes divide bacteriocins into three classes lantibiotics (class I), heat-stable non-lantibiotics (class II) and heat-labile antimicrobial proteins (class III), of which the majority of bacteriocins belong either to class I or class II. NMR spectroscopy has been applied in numerous studies of bacteriocins and an overview of the range of diversity in the 3D structures that have been determined by NMR spectroscopy is provided in Figure 4. 

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