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|1f6g, 8 NMR models ()|
POTASSIUM CHANNEL (KCSA) FULL-LENGTH FOLD
The molecular architecture of the NH(2) and COOH termini of the prokaryotic potassium channel KcsA has been determined using site-directed spin-labeling methods and paramagnetic resonance EPR spectroscopy. Cysteine mutants were generated (residues 5-24 and 121-160) and spin labeled, and the X-band CW EPR spectra were obtained from liposome-reconstituted channels at room temperature. Data on probe mobility (DeltaHo(-1)), accessibility parameters (PiO(2) and PiNiEdda), and inter-subunit spin-spin interaction (Omega) were used as structural constraints to build a three-dimensional folding model of these cytoplasmic domains from a set of simulated annealing and restrained molecular dynamics runs. 32 backbone structures were generated and averaged using fourfold symmetry, and a final mean structure was obtained from the eight lowest energy runs. Based on the present data, together with information from the KcsA crystal structure, a model for the three-dimensional fold of full-length KcsA was constructed. In this model, the NH(2) terminus of KcsA forms an alpha-helix anchored at the membrane-water interface, while the COOH terminus forms a right-handed four-helix bundle that extend some 40-50 A towards the cytoplasm. Functional analysis of COOH-terminal deletion constructs suggest that, while the COOH terminus does not play a substantial role in determining ion permeation properties, it exerts a modulatory role in the pH-dependent gating mechanism.
Molecular architecture of full-length KcsA: role of cytoplasmic domains in ion permeation and activation gating., Cortes DM, Cuello LG, Perozo E, J Gen Physiol. 2001 Feb;117(2):165-80. PMID:11158168
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
1f6g is a 4 chain structure with sequence from Streptomyces lividans. The February 2003 RCSB PDB Molecule of the Month feature on Potassium Channels by Shuchismita Dutta and David S. Goodsell is 10.2210/rcsb_pdb/mom_2003_2. Full experimental information is available from OCA.
- Cortes DM, Cuello LG, Perozo E. Molecular architecture of full-length KcsA: role of cytoplasmic domains in ion permeation and activation gating. J Gen Physiol. 2001 Feb;117(2):165-80. PMID:11158168
- Ursell T, Huang KC, Peterson E, Phillips R. Cooperative gating and spatial organization of membrane proteins through elastic interactions. PLoS Comput Biol. 2007 May;3(5):e81. PMID:17480116 doi:10.1371/journal.pcbi.0030081