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| | ==Crystal structure of CaiT R262E bound to gamma-butyrobetaine== | | ==Crystal structure of CaiT R262E bound to gamma-butyrobetaine== |
| - | <StructureSection load='4m8j' size='340' side='right' caption='[[4m8j]], [[Resolution|resolution]] 3.29Å' scene=''> | + | <StructureSection load='4m8j' size='340' side='right'caption='[[4m8j]], [[Resolution|resolution]] 3.29Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[4m8j]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Proteus_mirabilis_atcc_29906 Proteus mirabilis atcc 29906]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4M8J OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4M8J FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[4m8j]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Proteus_mirabilis_ATCC_29906 Proteus mirabilis ATCC 29906]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4M8J OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4M8J FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NM2:3-CARBOXY-N,N,N-TRIMETHYLPROPAN-1-AMINIUM'>NM2</scene></td></tr> | + | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NM2:3-CARBOXY-N,N,N-TRIMETHYLPROPAN-1-AMINIUM'>NM2</scene></td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">caiT, HMPREF0693_2800 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=525369 Proteus mirabilis ATCC 29906])</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=4m8j FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4m8j OCA], [https://pdbe.org/4m8j PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4m8j RCSB], [https://www.ebi.ac.uk/pdbsum/4m8j PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4m8j ProSAT]</span></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=4m8j FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4m8j OCA], [http://pdbe.org/4m8j PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4m8j RCSB], [http://www.ebi.ac.uk/pdbsum/4m8j PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4m8j ProSAT]</span></td></tr> | + | |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/C2LLR0_PROMI C2LLR0_PROMI]] Catalyzes the exchange of L-carnitine for gamma-butyrobetaine and related betaines (By similarity).[HAMAP-Rule:MF_01049] | + | [https://www.uniprot.org/uniprot/CAIT_PROMH CAIT_PROMH] Catalyzes the exchange of L-carnitine for gamma-butyrobetaine.[HAMAP-Rule:MF_01049]<ref>PMID:20829798</ref> <ref>PMID:24101465</ref> |
| | <div style="background-color:#fffaf0;"> | | <div style="background-color:#fffaf0;"> |
| | == Publication Abstract from PubMed == | | == Publication Abstract from PubMed == |
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| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Proteus mirabilis atcc 29906]] | + | [[Category: Large Structures]] |
| - | [[Category: Kalayil, S]] | + | [[Category: Proteus mirabilis ATCC 29906]] |
| - | [[Category: Cait]] | + | [[Category: Kalayil S]] |
| - | [[Category: Carnitine/gamma-butyrobetaine antiporter]]
| + | |
| - | [[Category: Leut fold]]
| + | |
| - | [[Category: Plasma membrane]]
| + | |
| - | [[Category: Transport protein]]
| + | |
| Structural highlights
Function
CAIT_PROMH Catalyzes the exchange of L-carnitine for gamma-butyrobetaine.[HAMAP-Rule:MF_01049][1] [2]
Publication Abstract from PubMed
Most secondary-active transporters transport their substrates using an electrochemical ion gradient. In contrast, the carnitine transporter (CaiT) is an ion-independent, l-carnitine/gamma-butyrobetaine antiporter belonging to the betaine/carnitine/choline transporter family of secondary transporters. Recently determined crystal structures of CaiT from Escherichia coli and Proteus mirabilis revealed an inverted five-transmembrane-helix repeat similar to that in the amino acid/Na+ symporter LeuT. The ion independence of CaiT makes it unique in this family. Here we show that mutations of arginine 262 (R262) make CaiT Na+-dependent. The transport activity of R262 mutants increased by 30-40% in the presence of a membrane potential, indicating substrate/Na+ cotransport. Structural and biochemical characterization revealed that R262 plays a crucial role in substrate binding by stabilizing the partly unwound TM1' helix. Modeling CaiT from P. mirabilis in the outward-open and closed states on the corresponding structures of the related symporter BetP reveals alternating orientations of the buried R262 sidechain, which mimic sodium binding and unbinding in the Na+-coupled substrate symporters. We propose that a similar mechanism is operative in other Na+/H+-independent transporters, in which a positively charged amino acid replaces the cotransported cation. The oscillation of the R262 sidechain in CaiT indicates how a positive charge triggers the change between outward-open and inward-open conformations as a unifying critical step in LeuT-type transporters.
Arginine oscillation explains Na+ independence in the substrate/product antiporter CaiT.,Kalayil S, Schulze S, Kuhlbrandt W Proc Natl Acad Sci U S A. 2013 Oct 7. PMID:24101465[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Schulze S, Koster S, Geldmacher U, Terwisscha van Scheltinga AC, Kuhlbrandt W. Structural basis of Na(+)-independent and cooperative substrate/product antiport in CaiT. Nature. 2010 Sep 9;467(7312):233-6. PMID:20829798 doi:10.1038/nature09310
- ↑ Kalayil S, Schulze S, Kuhlbrandt W. Arginine oscillation explains Na+ independence in the substrate/product antiporter CaiT. Proc Natl Acad Sci U S A. 2013 Oct 7. PMID:24101465 doi:http://dx.doi.org/10.1073/pnas.1309071110
- ↑ Kalayil S, Schulze S, Kuhlbrandt W. Arginine oscillation explains Na+ independence in the substrate/product antiporter CaiT. Proc Natl Acad Sci U S A. 2013 Oct 7. PMID:24101465 doi:http://dx.doi.org/10.1073/pnas.1309071110
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