%0 Journal Article
%A Zamora-Carreras, Héctor
%A Maestro García-Donas, María Beatriz
%A Strandberg, Eric
%A Ulrich, Anne
%A Sanz, Jesús
%A Jiménez, María Angeles
%T Micelle-triggered beta-hairpin to alpha-helix transition in a 14-residue peptide from a choline-binding repeat of the pneumococcal autolysin LytA
%D 2015
%@ 0947-6539
%U https://hdl.handle.net/20.500.14352/92617.2
%X Choline-binding modules (CBMs) have a ββ-solenoid structure composed of choline-binding repeats (CBR), which consist of a β-hairpin followed by a short linker. To find minimal peptides that are able to maintain the CBR native structure and to evaluate their remaining choline-binding ability, we have analysed the third β-hairpin of the CBM from the pneumococcal LytA autolysin. Circular dichroism and NMR data reveal that this peptide forms a highly stable native-like β-hairpin both in aqueous solution and in the presence of trifluoroethanol, but, strikingly, the peptide structure is a stable amphipathic α-helix in both zwitterionic (dodecylphosphocholine) and anionic (sodium dodecylsulfate) detergent micelles, as well as in small unilamellar vesicles. This β-hairpin to α-helix conversion is reversible. Given that the β-hairpin and α-helix differ greatly in the distribution of hydrophobic and hydrophilic side chains, we propose that the amphipathicity is a requirement for a peptide structure to interact and to be stable in micelles or lipid vesicles. To our knowledge, this "chameleonic" behaviour is the only described case of a micelle-induced structural transition between two ordered peptide structures.
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