Abstract
We report the crystal structure of the nonselective cation channel NaK from Bacillus cereus at a resolution of 1.6 Å. The structure reveals the intracellular gate in an open state, as opposed to the closed form reported previously, making NaK the only channel for which the three-dimensional structures of both conformations are known. Channel opening follows a conserved mechanism of inner helix bending using a flexible glycine residue, the gating hinge, seen in MthK and most other tetrameric cation channels. Additionally, distinct inter and intrasubunit rearrangements involved in channel gating are seen and characterized for the first time along with inner helix twisting motions. Furthermore, we identify a residue deeper within the cavity of the channel pore, Phe92, which is likely to form a constriction point within the open pore, restricting ion flux through the channel. Mutating this residue to alanine causes a subsequent increase in ion-conduction rates as measured by 86Rb flux assays. The structures of both the open and closed conformations of the NaK channel correlate well with those of equivalent K + channel conformations, namely MthK and KcsA, respectively.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 30-34 |
| Number of pages | 5 |
| Journal | Nature Structural and Molecular Biology |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 2009 |
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ASJC Scopus subject areas
- Structural Biology
- Molecular Biology
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High-resolution structure of the open NaK channel. / Alam, Amer; Jiang, Youxing.
In: Nature Structural and Molecular Biology, Vol. 16, No. 1, 01.2009, p. 30-34.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - High-resolution structure of the open NaK channel
AU - Alam, Amer
AU - Jiang, Youxing
PY - 2009/1
Y1 - 2009/1
N2 - We report the crystal structure of the nonselective cation channel NaK from Bacillus cereus at a resolution of 1.6 Å. The structure reveals the intracellular gate in an open state, as opposed to the closed form reported previously, making NaK the only channel for which the three-dimensional structures of both conformations are known. Channel opening follows a conserved mechanism of inner helix bending using a flexible glycine residue, the gating hinge, seen in MthK and most other tetrameric cation channels. Additionally, distinct inter and intrasubunit rearrangements involved in channel gating are seen and characterized for the first time along with inner helix twisting motions. Furthermore, we identify a residue deeper within the cavity of the channel pore, Phe92, which is likely to form a constriction point within the open pore, restricting ion flux through the channel. Mutating this residue to alanine causes a subsequent increase in ion-conduction rates as measured by 86Rb flux assays. The structures of both the open and closed conformations of the NaK channel correlate well with those of equivalent K + channel conformations, namely MthK and KcsA, respectively.
AB - We report the crystal structure of the nonselective cation channel NaK from Bacillus cereus at a resolution of 1.6 Å. The structure reveals the intracellular gate in an open state, as opposed to the closed form reported previously, making NaK the only channel for which the three-dimensional structures of both conformations are known. Channel opening follows a conserved mechanism of inner helix bending using a flexible glycine residue, the gating hinge, seen in MthK and most other tetrameric cation channels. Additionally, distinct inter and intrasubunit rearrangements involved in channel gating are seen and characterized for the first time along with inner helix twisting motions. Furthermore, we identify a residue deeper within the cavity of the channel pore, Phe92, which is likely to form a constriction point within the open pore, restricting ion flux through the channel. Mutating this residue to alanine causes a subsequent increase in ion-conduction rates as measured by 86Rb flux assays. The structures of both the open and closed conformations of the NaK channel correlate well with those of equivalent K + channel conformations, namely MthK and KcsA, respectively.
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U2 - 10.1038/nsmb.1531
DO - 10.1038/nsmb.1531
M3 - Article
VL - 16
SP - 30
EP - 34
JO - Nature Structural and Molecular Biology
JF - Nature Structural and Molecular Biology
SN - 1545-9993
IS - 1
ER -