Models of the structure and gating mechanisms of the pore domain of the NaChBac ion channel.
The NaChBac prokaryotic sodium channel appears to be a descendent of an evolutionary link between voltage-gated K(V) and Ca(V) channels. Like K(V) channels, four identical six-transmembrane subunits comprise the NaChBac channel, but its selectivity filter possesses a signature sequence of eukaryotic Ca(V) channels. We developed structural models of the NaChBac channel in closed and open conformations, using K(+)-channel crystal structures as initial templates. Our models were also consistent with numerous experimental results and modeling criteria. This study concerns the pore domain. The major differences between our models and K(+) crystal structures involve the latter portion of the selectivity filter and the bend region in S6 of the open conformation. These NaChBac models may serve as a stepping stone between K(+) channels of known structure and Na(V), Ca(V), and TRP channels of unknown structure.
Shafrir
Yinon
Y
Laboratory of Cell Biology, CCR, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-5567, USA.
Durell
Stewart R
SR
Guy
H Robert
HR
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001407:Bacillus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D003198:Computer Simulation; D017124:Conserved Sequence; D015640:Ion Channel Gating; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D015222:Sodium Channels / Q000737:chemistry* / Q000378:metabolism*
D001426:Bacterial Proteins; D050505:Mutant Proteins; C443666:NaChBac protein, bacteria; D021122:Protein Subunits; D015222:Sodium Channels