The structure of the lipoaminopeptaibol helioferin, an antibiotic peptide from Mycogone rosea
What is it about?
In this work we describe the determined and refined at atomic resolution structure of the nonapeptide antibiotics helioferins A and B isolated from a natural biological source and co-crystallized with molar ratio 1:1. The peptides are expected to be positively charged as they bind fluoride and chloride anions with molar ratio 0.67:0.33. We have also compared the structure with that of the decapeptide leucinostatin A, which is the only other structure of a lipoaminopeptide known to date.
Why is it important?
Helioferin and the earlier determined structure of the homologous leucinostatin A have total straight length of about 21 Å. This implies that their membrane-modifying antibiotic activity may not obey the pore-forming, barrel stave model. The latter model generally applies for the bioactivity of long peptaibols. In contrast, shorter lipoaminopeptide antibiotics may act via a concentration dependent aggregation in the membranes (carpet mechanism).