PMID: 23019149

Authors:

Gessmann R, Axford D, Evans G, Bruckner H, Petratos K

Title:

The crystal structure of samarosporin I at atomic resolution.

Journal:

J Pept Sci. 2012 Nov;18(11):678-84. doi: 10.1002/psc.2454. Epub 2012 Sep 28.

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 3(10) -helical and a minor fraction of alpha-helical conformation. The helices are significantly bent and packed in an antiparallel fashion in the centered monoclinic lattice leaving among them an approximately 10-A 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. Copyright (c) 2012 European Peptide Society and John Wiley & Sons, Ltd.