Sandbox Reserved 1069: Difference between revisions
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[[Image:YiiP_Mechanism.png|300px|right|thumb| General mechanism for Zn<sup>2+</sup>/H<sup>+</sup> antiport]] | [[Image:YiiP_Mechanism.png|300px|right|thumb| General mechanism for Zn<sup>2+</sup>/H<sup>+</sup> antiport]] | ||
YiiP's ability to export Zn<sup>2+</sup> from the cytoplasm is best described as an alternating access mechanism with Zn<sup>2+</sup>/H<sup>+</sup> antiport. YiiP has 2 major structural conformations as shown by the crystallized structures [http://proteopedia.org/wiki/index.php/3h90 3H90] and [http://proteopedia.org/wiki/index.php/3j1z 3J1Z] <ref>PMID:23341604</ref> (a YiiP homolog derived from ''Shewanella oneidensis''). 3H90 shows YiiP in its outward-facing conformation and 3J1Z shows the YiiP homolog in an inward-facing conformation. | YiiP's ability to export Zn<sup>2+</sup> from the cytoplasm is best described as an alternating access mechanism with Zn<sup>2+</sup>/H<sup>+</sup> antiport. YiiP has 2 major structural conformations as shown by the crystallized structures [http://proteopedia.org/wiki/index.php/3h90 3H90] and [http://proteopedia.org/wiki/index.php/3j1z 3J1Z] <ref>PMID:23341604</ref> (a YiiP homolog derived from ''Shewanella oneidensis''). 3H90 shows YiiP in its outward-facing conformation with Zn<sup>2+</sup> present and 3J1Z shows the YiiP homolog in an inward-facing conformation where there is no Zn<sup>2+</sup> present. | ||
When YiiP is saturated with Zn<sup>2+</sup> it favors the <scene name='69/694236/Outward-facinggreen/1'>outward-facing conformation</scene> whereas when active sites are either empty or bound to H<sup>+</sup> the <scene name='69/694236/Inward-facinggreen/1'>inward-facing conformation</scene> is favored. This drives the export of Zn<sup>2+</sup> from the cytoplasm and enhances the coupling of the proton-motive force. Although YiiP exists as a homodimer both monomers can undergo conformation change independent of one other to | When YiiP is saturated with Zn<sup>2+</sup> it favors the <scene name='69/694236/Outward-facinggreen/1'>outward-facing conformation</scene> whereas when active sites are either empty or bound to H<sup>+</sup> the <scene name='69/694236/Inward-facinggreen/1'>inward-facing conformation</scene> is favored. This drives the export of Zn<sup>2+</sup> from the cytoplasm and enhances the coupling of the proton-motive force. Although YiiP exists as a homodimer both monomers can undergo conformation change independent of one other to | ||
produce the alternating access mechanism. | produce the alternating access mechanism. | ||
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===Zn<sup>2+</sup> Induced Conformation Change=== | ===Zn<sup>2+</sup> Induced Conformation Change=== | ||
Zinc induced conformation changes in the TMD and CTD leads to the major <scene name='69/694236/Outward-facinggreen/1'>outward-facing</scene> and <scene name='69/694236/Inward-facinggreen/1'>inward-facing conformations</scene>. [[Image:InwardVsOutward.png|300px|right|thumb| Pivoting TM helices highlighted in yellow]] | |||
The conformation change directly involved with Zn<sup>2+</sup>/H<sup>+</sup> antiport occurs in the TMD as helix pivoting controls what environment site A is available to. Conformation change occurs when the transmembrane helix pairs TM1, TM2, TM4, and TM5 pivot around cation binding site A.<ref>PMID:23341604</ref> | The conformation change directly involved with Zn<sup>2+</sup>/H<sup>+</sup> antiport occurs in the TMD as helix pivoting controls what environment site A is available to. Conformation change occurs when the transmembrane helix pairs TM1, TM2, TM4, and TM5 pivot around cation binding site A.<ref>PMID:23341604</ref> | ||