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Systematic comparison of molecular conformations of H+,K+-ATPase reveals an important contribution of the A-M2 linker for the luminal gating.

Abe K, Tani K, Fujiyoshi Y - J. Biol. Chem. (2014)

Bottom Line: The molecular conformation of the (SCH)E2·MgF state thus represents a mixed overall structure in which its cytoplasmic and luminal half appear to be independently modulated by a phosphate analog and an antagonist bound to the respective parts of the enzyme.Comparison of the molecular conformations revealed that the linker region connecting the A domain and the transmembrane helix 2 (A-M2 linker) mediates the regulation of luminal gating.The mechanistic rationale underlying luminal gating observed in H(+),K(+)-ATPase is consistent with that observed in sarcoplasmic reticulum Ca(2+)-ATPase and other P-type ATPases and is most likely conserved for the P-type ATPase family in general.

View Article: PubMed Central - PubMed

Affiliation: From the Cellular and Structural Physiology Institute and Graduate School of Pharmaceutical Science, Nagoya University, Nagoya 464-8601, Japan kabe@cespi.nagoya-u.ac.jp.

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Comparisons of the TM helices.A–D, cross-sections parallel to the membrane plane for the luminal TM region of the indicated conformational states (A, (SCH)E2·BeF; B, (SCH)E2·MgF; C, E2·AlF; D, (Rb+)E2·AlF) is viewed from the luminal side of the membrane, with their homology models superimposed (ribbons). Mesh represents the outer surface of the EM maps (1σ). The surface color in the cross-sections indicates the contour level at the indicated plane, gradually changing from blue (1 σ) to red (4.2 σ) as indicated on the lower right. For comparison of the arrangement of TM helices in each state, a homology model for the (SCH)E2·BeF state (magenta ribbon) is shown in all panels. Green and blue arrows in C and D indicate displacement of the TM helices from the (SCH)E2·BeF to E2·AlF and (Rb+)E2·AlF states, respectively. Schematic representations of their conformational states are shown on the upper left of each panel (see Fig. 9 for details).
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Figure 5: Comparisons of the TM helices.A–D, cross-sections parallel to the membrane plane for the luminal TM region of the indicated conformational states (A, (SCH)E2·BeF; B, (SCH)E2·MgF; C, E2·AlF; D, (Rb+)E2·AlF) is viewed from the luminal side of the membrane, with their homology models superimposed (ribbons). Mesh represents the outer surface of the EM maps (1σ). The surface color in the cross-sections indicates the contour level at the indicated plane, gradually changing from blue (1 σ) to red (4.2 σ) as indicated on the lower right. For comparison of the arrangement of TM helices in each state, a homology model for the (SCH)E2·BeF state (magenta ribbon) is shown in all panels. Green and blue arrows in C and D indicate displacement of the TM helices from the (SCH)E2·BeF to E2·AlF and (Rb+)E2·AlF states, respectively. Schematic representations of their conformational states are shown on the upper left of each panel (see Fig. 9 for details).

Mentions: Like in the (SCH)E2·BeF state, bound SCH28080 imposed a luminal-open conformation of TM helices in the (SCH)E2·MgF state (Fig. 5, A and B). Comparison between the luminal-open conformation of the SCH28080-bound forms and the luminal-closed conformation of E2·AlF and (Rb+)E2·AlF revealed that opening and closing of the luminal helices was accomplished by rearranging the M1-M4 helices (Fig. 5, C and D). During the transition from an open to closed form of the luminal helices, the luminal half of the M3M4 helices was shifted laterally to close the SCH28080-binding site, which was coupled with the movement of the M1M2 helices (see Fig. 5, C and D, green and blue arrows).


Systematic comparison of molecular conformations of H+,K+-ATPase reveals an important contribution of the A-M2 linker for the luminal gating.

Abe K, Tani K, Fujiyoshi Y - J. Biol. Chem. (2014)

Comparisons of the TM helices.A–D, cross-sections parallel to the membrane plane for the luminal TM region of the indicated conformational states (A, (SCH)E2·BeF; B, (SCH)E2·MgF; C, E2·AlF; D, (Rb+)E2·AlF) is viewed from the luminal side of the membrane, with their homology models superimposed (ribbons). Mesh represents the outer surface of the EM maps (1σ). The surface color in the cross-sections indicates the contour level at the indicated plane, gradually changing from blue (1 σ) to red (4.2 σ) as indicated on the lower right. For comparison of the arrangement of TM helices in each state, a homology model for the (SCH)E2·BeF state (magenta ribbon) is shown in all panels. Green and blue arrows in C and D indicate displacement of the TM helices from the (SCH)E2·BeF to E2·AlF and (Rb+)E2·AlF states, respectively. Schematic representations of their conformational states are shown on the upper left of each panel (see Fig. 9 for details).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 5: Comparisons of the TM helices.A–D, cross-sections parallel to the membrane plane for the luminal TM region of the indicated conformational states (A, (SCH)E2·BeF; B, (SCH)E2·MgF; C, E2·AlF; D, (Rb+)E2·AlF) is viewed from the luminal side of the membrane, with their homology models superimposed (ribbons). Mesh represents the outer surface of the EM maps (1σ). The surface color in the cross-sections indicates the contour level at the indicated plane, gradually changing from blue (1 σ) to red (4.2 σ) as indicated on the lower right. For comparison of the arrangement of TM helices in each state, a homology model for the (SCH)E2·BeF state (magenta ribbon) is shown in all panels. Green and blue arrows in C and D indicate displacement of the TM helices from the (SCH)E2·BeF to E2·AlF and (Rb+)E2·AlF states, respectively. Schematic representations of their conformational states are shown on the upper left of each panel (see Fig. 9 for details).
Mentions: Like in the (SCH)E2·BeF state, bound SCH28080 imposed a luminal-open conformation of TM helices in the (SCH)E2·MgF state (Fig. 5, A and B). Comparison between the luminal-open conformation of the SCH28080-bound forms and the luminal-closed conformation of E2·AlF and (Rb+)E2·AlF revealed that opening and closing of the luminal helices was accomplished by rearranging the M1-M4 helices (Fig. 5, C and D). During the transition from an open to closed form of the luminal helices, the luminal half of the M3M4 helices was shifted laterally to close the SCH28080-binding site, which was coupled with the movement of the M1M2 helices (see Fig. 5, C and D, green and blue arrows).

Bottom Line: The molecular conformation of the (SCH)E2·MgF state thus represents a mixed overall structure in which its cytoplasmic and luminal half appear to be independently modulated by a phosphate analog and an antagonist bound to the respective parts of the enzyme.Comparison of the molecular conformations revealed that the linker region connecting the A domain and the transmembrane helix 2 (A-M2 linker) mediates the regulation of luminal gating.The mechanistic rationale underlying luminal gating observed in H(+),K(+)-ATPase is consistent with that observed in sarcoplasmic reticulum Ca(2+)-ATPase and other P-type ATPases and is most likely conserved for the P-type ATPase family in general.

View Article: PubMed Central - PubMed

Affiliation: From the Cellular and Structural Physiology Institute and Graduate School of Pharmaceutical Science, Nagoya University, Nagoya 464-8601, Japan kabe@cespi.nagoya-u.ac.jp.

Show MeSH