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| | ==Ammonia permeable aquaporin AtTIP2;1== | | ==Ammonia permeable aquaporin AtTIP2;1== |
| - | <StructureSection load='5i32' size='340' side='right' caption='[[5i32]], [[Resolution|resolution]] 1.18Å' scene=''> | + | <StructureSection load='5i32' size='340' side='right'caption='[[5i32]], [[Resolution|resolution]] 1.18Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[5i32]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5I32 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5I32 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[5i32]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5I32 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5I32 FirstGlance]. <br> |
| - | </td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5i32 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5i32 OCA], [http://pdbe.org/5i32 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5i32 RCSB], [http://www.ebi.ac.uk/pdbsum/5i32 PDBsum]</span></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.18Å</td></tr> |
| | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5i32 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5i32 OCA], [https://pdbe.org/5i32 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5i32 RCSB], [https://www.ebi.ac.uk/pdbsum/5i32 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5i32 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/TIP21_ARATH TIP21_ARATH]] Aquaporin required to facilitate the transport of water from the vacuolar compartment to the cytoplasm. Does not promote glycerol permability. Its function is impaired by Hg(2+). Transports urea in yeast cells and Xenopus laevis oocytes in a pH-independent manner. Transports methylammonium or ammonium in yeast cells and Xenopus laevis oocytes, preferentially at high medium pH. May participate in vacuolar compartmentation and detoxification of ammonium.<ref>PMID:14576283</ref> <ref>PMID:15665250</ref> <ref>PMID:8624437</ref> | + | [https://www.uniprot.org/uniprot/TIP21_ARATH TIP21_ARATH] Aquaporin required to facilitate the transport of water from the vacuolar compartment to the cytoplasm. Does not promote glycerol permability. Its function is impaired by Hg(2+). Transports urea in yeast cells and Xenopus laevis oocytes in a pH-independent manner. Transports methylammonium or ammonium in yeast cells and Xenopus laevis oocytes, preferentially at high medium pH. May participate in vacuolar compartmentation and detoxification of ammonium.<ref>PMID:14576283</ref> <ref>PMID:15665250</ref> <ref>PMID:8624437</ref> |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
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| | </div> | | </div> |
| | <div class="pdbe-citations 5i32" style="background-color:#fffaf0;"></div> | | <div class="pdbe-citations 5i32" style="background-color:#fffaf0;"></div> |
| | + | |
| | + | ==See Also== |
| | + | *[[Aquaporin 3D structures|Aquaporin 3D structures]] |
| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Gourdon, P]] | + | [[Category: Arabidopsis thaliana]] |
| - | [[Category: Johanson, U]] | + | [[Category: Large Structures]] |
| - | [[Category: Kirscht, A]] | + | [[Category: Gourdon P]] |
| - | [[Category: Kjellbom, P]]
| + | [[Category: Johanson U]] |
| - | [[Category: Nissen, P]] | + | [[Category: Kirscht A]] |
| - | [[Category: Ammonia-permeable]] | + | [[Category: Kjellbom P]] |
| - | [[Category: Aquaporin]] | + | [[Category: Nissen P]] |
| - | [[Category: Membrane protein]] | + | |
| - | [[Category: Mip]]
| + | |
| Structural highlights
Function
TIP21_ARATH Aquaporin required to facilitate the transport of water from the vacuolar compartment to the cytoplasm. Does not promote glycerol permability. Its function is impaired by Hg(2+). Transports urea in yeast cells and Xenopus laevis oocytes in a pH-independent manner. Transports methylammonium or ammonium in yeast cells and Xenopus laevis oocytes, preferentially at high medium pH. May participate in vacuolar compartmentation and detoxification of ammonium.[1] [2] [3]
Publication Abstract from PubMed
Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 A resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants.
Crystal Structure of an Ammonia-Permeable Aquaporin.,Kirscht A, Kaptan SS, Bienert GP, Chaumont F, Nissen P, de Groot BL, Kjellbom P, Gourdon P, Johanson U PLoS Biol. 2016 Mar 30;14(3):e1002411. doi: 10.1371/journal.pbio.1002411., eCollection 2016 Mar. PMID:27028365[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Liu LH, Ludewig U, Gassert B, Frommer WB, von Wiren N. Urea transport by nitrogen-regulated tonoplast intrinsic proteins in Arabidopsis. Plant Physiol. 2003 Nov;133(3):1220-8. Epub 2003 Oct 23. PMID:14576283 doi:http://dx.doi.org/10.1104/pp.103.027409
- ↑ Loque D, Ludewig U, Yuan L, von Wiren N. Tonoplast intrinsic proteins AtTIP2;1 and AtTIP2;3 facilitate NH3 transport into the vacuole. Plant Physiol. 2005 Feb;137(2):671-80. Epub 2005 Jan 21. PMID:15665250 doi:http://dx.doi.org/pp.104.051268
- ↑ Daniels MJ, Chaumont F, Mirkov TE, Chrispeels MJ. Characterization of a new vacuolar membrane aquaporin sensitive to mercury at a unique site. Plant Cell. 1996 Apr;8(4):587-99. PMID:8624437 doi:http://dx.doi.org/10.1105/tpc.8.4.587
- ↑ Kirscht A, Kaptan SS, Bienert GP, Chaumont F, Nissen P, de Groot BL, Kjellbom P, Gourdon P, Johanson U. Crystal Structure of an Ammonia-Permeable Aquaporin. PLoS Biol. 2016 Mar 30;14(3):e1002411. doi: 10.1371/journal.pbio.1002411., eCollection 2016 Mar. PMID:27028365 doi:http://dx.doi.org/10.1371/journal.pbio.1002411
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