Antimicrobial peptides produced by lactic acid bacteria (LAB) are extensively studied, but little is know about their three-dimensional structures. Solution structures of these peptides will be useful to gain information about their mode of action, which again is important for further use of these substances in industry and medicine. Curvacin A is an antimicrobial peptide that belongs to the family of pediocin-like bacteriocins.
Curvacin A was produced from its natural LAB producer, Lactobacillus curvatus LTH1174, and purified by ion-exchange- and reverse phase chromatography. Circular Dichroism-experiments revealed that curvacin A was unstructured in water, but became structured upon interactions with membrane-mimicking environments such as dodecyl phosphocholin (DPC)-micelles.
The three-dimensional structure of curvacin A in DPC-micelles has been elucidated by the use of nuclear magnetic resonance (NMR)-spectroscopy. Curvacin A was shown to contain three regions: an N-terminal S-shaped ƒÒ-sheet like domain (residues 2-15), a central polar helix (residues 19-24) and an amphiphilic C-terminal helix (residues 29-39). The C-terminal tail consists of only two residues (G40 and M41) and seems to be unstructured. There was a hinge between the three regions, enabling the regions to move relative to each other.