Table 10.
Classification of class 1 linear antimicrobial peptides (UCLL1)
| Subclass | Modification sitea |
Modification type |
Sub-type | Peptide examples |
|---|---|---|---|---|
| UCLL1A | None | None | Not-AA-richb | LL-37 |
| AA-Rich (25%) | Pro-rich; Arg-rich PR-39 | |||
| UCLL1B | Sidechain | Group attachment |
Hydroxylation; halogenation; phosphorylation ; glycosylation; lipidation; sulfation |
Piscidin 4 (hydroxylated Trp); datucin, MccC7 |
| Sidechain cyclization |
cyclic glutamate | Heliocin | ||
| UCLL1C | Backbone | End capping | Amidation; acetylation; other attachments |
Aurein 1.2; temproin A |
| Configuration change |
D-amino acids, | Gramicidin; bombinin H4 | ||
| Backbone transformed |
Dehydrated; | Cypemycin (Linaridins) | ||
| Heterocyclic rings |
Thiopeptides in ThioBase |
a
Post-translational modification (PTM) is a broad concept that includes all types of functional groups attached to the peptide chain via covalent bond formation. A detailed list of PTMs is provided in Table 5. Some common examples are N-terminal acetylation, C-terminal amidation, phosphorylation, glycosylation, aromatic halogenation, and sulfation. In the extreme case, even the peptide backbone is modified, leading to dehydrated or heterocycles. However, all these modifications are limited to a single amino acid and do not lead to a polypeptide chain connection between different amino acids as observed in the other three major classes of AMPs (Table 9).
b
AA = Amino acids.