6evh

Publication Abstract from PubMed

The crystal structure of the natural nonapeptide antibiotic helioferin has been determined and refined to 0.9 A resolution. Helioferin consists of helioferin A and B, which contain 2-(2'-aminopropyl)aminoethanol (Apae) and 2-[(2'-aminopropyl)methylamino]ethanol (Amae) at their respective alkanolamine termini. In addition, helioferin contains the unusual amino-acid residues alpha-aminoisobutyric acid (Aib) and (2S,4S,6S)-2-amino-6-hydroxy-4-methyl-8-oxodecanoic acid (Ahmod). The amino-terminus is capped with 2-methyl-n-1-octanoic acid (M8a). The peptide crystallizes with a 1:1 molar ratio of helioferin A and B in the monoclinic space group C2, with unit-cell parameters a = 34.711, b = 10.886, c = 17.150 A, beta = 93.05 degrees . The peptide backbone folds in a regular right-handed alpha-helical conformation, with eight intramolecular hydrogen bonds, all but one forming 5-->1 interactions. The two aliphatic chains of the fatty-acyl (M8a) and the second residue (Ahmod) extend out of the alpha-helical structure in opposite directions and lead to a corkscrew-like shape of the peptide molecule. Halogen anions (Cl(-) and F(-)) have been co-crystallized with the peptide molecules, implying a positive charge at the aminoalcohol end of the peptide. In the tightly packed crystal the helices are linked head to tail via the anions by electrostatic, hydrogen-bond and van der Waals interactions, forming continuous helical rods. Two nonparallel rods (forming an angle of 118 degrees ) interact directly via hydrogen bonds and via the anions, forming a double layer. Successive double layers are held together only via van der Waals contacts. The helical axes of successive double layers are also related by an angle of 118 degrees . The structure of helioferin reported here and the previously determined structure of the homologous leucinostatin A have a total straight length of about 21 A, indicating a different membrane-modifying bioactivity from that of long-chain, amphiphilic peptaibols.

The crystal structure of the lipoaminopeptaibol helioferin, an antibiotic peptide from Mycogone rosea.,Gessmann R, Bruckner H, Berg A, Petratos K Acta Crystallogr D Struct Biol. 2018 Apr 1;74(Pt 4):315-320. doi:, 10.1107/S2059798318001857. Epub 2018 Apr 3. PMID:29652258^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.