The conducting form of gramicidin A is a right-handed double-stranded double helix.
The linear pentadecapeptide antibiotic, gramicidin D, is a naturally occurring product of Bacillus brevis known to form ion channels in synthetic and natural membranes. The x-ray crystal structures of the right-handed double-stranded double-helical dimers (DSDH) reported here agree with 15N-NMR and CD data on the functional gramicidin D channel in lipid bilayers. These structures demonstrate single-file ion transfer through the channels. The results also indicate that previous crystal structure reports of a left-handed double-stranded double-helical dimer in complex with Cs+ and K+ salts may be in error and that our evidence points to the DSDH as the major conformer responsible for ion transport in membranes.
Burkhart
B M
BM
Hauptman-Woodward Medical Research Institute, Inc., 73 High Street, Buffalo, NY 14203, USA. burkhart@hwi.buffalo.edu
Li
N
N
Langs
D A
DA
Pangborn
W A
WA
Duax
W L
WL
D000595:Amino Acid Sequence; D002586:Cesium; D002942:Circular Dichroism; D018360:Crystallography, X-Ray / Q000379:methods; D006096:Gramicidin / Q000737:chemistry*; D008051:Lipid Bilayers; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011188:Potassium / Q000737:chemistry; D017433:Protein Structure, Secondary; D015203:Reproducibility of Results; D055672:Static Electricity; D013499:Surface Properties
D008051:Lipid Bilayers; D006096:Gramicidin; D002586:Cesium; D011188:Potassium