Micelle-Triggered β-Hairpin to α-Helix Transition in a 14-Residue Peptide from a Choline-Binding Repeat of the Pneumococcal Autolysin LytA.
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.
Instituto de Química Física Rocasolano (IQFR), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 119, 28006-Madrid (Spain).
Héctor
H
Zamora-Carreras
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202-Alicante (Spain).
Beatriz
B
Maestro
Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O.B. 3640, 76021 Karlsruhe (Germany).
Erik
E
Strandberg
Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O.B. 3640, 76021 Karlsruhe (Germany).|Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe (Germany).
Anne S
AS
Ulrich
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202-Alicante (Spain).
Jesús M
JM
Sanz
Instituto de Química Física Rocasolano (IQFR), Consejo Superior de Investigaciones Científicas (CSIC), Serrano 119, 28006-Madrid (Spain). majimenez@iqfr.csic.es.
M Ángeles
MÁ
Jiménez
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002794:Choline / Q000378:metabolism*; D002942:Circular Dichroism; D006801:Humans; D008823:Micelles; D008958:Models, Molecular; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000737:chemistry* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D011008:Pneumococcal Infections / Q000382:microbiology; D017433:Protein Structure, Secondary; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013296:Streptococcus pneumoniae / Q000737:chemistry* / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry; D014270:Trifluoroethanol / Q000737:chemistry
D001426:Bacterial Proteins; D008823:Micelles; D010455:Peptides; D013501:Surface-Active Agents; D010767:Phosphorylcholine; D012967:Sodium Dodecyl Sulfate; C028810:dodecylphosphocholine; D014270:Trifluoroethanol; D009238:N-Acetylmuramoyl-L-alanine Amidase; D002794:Choline
micelles; protein folding; protein structures; structural biology; structural elucidation