title: The crystal structure of samarosporin I at atomic resolution.
abstract: The atomic resolution structures of samarosporin I have been determined at 100 and 293 K. This is the first crystal structure of a natural 15-residue peptaibol. The amino acid sequence in samarosporin I is identical to emerimicin IV and stilbellin I. Samarosporin is a peptide antibiotic produced by the ascomycetous fungus Samarospora rostrup and belongs to peptaibol subfamily 2. The structures at both temperatures are very similar to each other adopting mainly a 3₁₀-helical and a minor fraction of α-helical conformation. The helices are significantly bent and packed in an antiparallel fashion in the centered monoclinic lattice leaving among them an approximately 10-Å channel extending along the crystallographic twofold axis. Only two ordered water molecules per peptide molecule were located in the channel. Comparisons have been carried out with crystal structures of subfamily 2 16-residue peptaibols antiamoebin and cephaibols. The repercussion of the structural analysis of samarosporin on membrane function is discussed.
authors.affiliation: IMBB-FORTH, N. Plastira 100, Heraklion 70013, Greece.
authors.forename: Renate
authors.initials: R
authors.lastname: Gessmann
authors.forename: Danny
authors.initials: D
authors.lastname: Axford
authors.forename: Gwyndaf
authors.initials: G
authors.lastname: Evans
authors.forename: Hans
authors.initials: H
authors.lastname: Brückner
authors.forename: Kyriacos
authors.initials: K
authors.lastname: Petratos
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D054848:Peptaibols / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D016415:Sequence Alignment
chemical_list: D023181:Antimicrobial Cationic Peptides; D054848:Peptaibols; D010455:Peptides; C013245:samarosporin