|
|
| (3 intermediate revisions not shown.) |
| Line 1: |
Line 1: |
| | + | |
| | ==X-ray crystal structure of a slow cyanobacterial Cl-/H+ antiporter== | | ==X-ray crystal structure of a slow cyanobacterial Cl-/H+ antiporter== |
| - | <StructureSection load='3nd0' size='340' side='right' caption='[[3nd0]], [[Resolution|resolution]] 3.20Å' scene=''> | + | <StructureSection load='3nd0' size='340' side='right'caption='[[3nd0]], [[Resolution|resolution]] 3.20Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[3nd0]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Synechocystis Synechocystis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ND0 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3ND0 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[3nd0]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechocystis_sp._PCC_6803 Synechocystis sp. PCC 6803]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ND0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ND0 FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene></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]] 3.2Å</td></tr> |
| - | <tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">sll0855 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1142 Synechocystis])</td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene></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=3nd0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3nd0 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3nd0 RCSB], [http://www.ebi.ac.uk/pdbsum/3nd0 PDBsum]</span></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=3nd0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3nd0 OCA], [https://pdbe.org/3nd0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3nd0 RCSB], [https://www.ebi.ac.uk/pdbsum/3nd0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3nd0 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| - | <div style="background-color:#fffaf0;">
| + | == Function == |
| - | == Publication Abstract from PubMed == | + | [https://www.uniprot.org/uniprot/P73745_SYNY3 P73745_SYNY3] |
| - | X-ray crystal structures have been previously determined for three CLC-type transporter homologues, but the absolute unitary transport rate is known for only one of these. The Escherichia coli Cl(-)/H(+) antiporter (EC) moves approximately 2000 Cl(-) ions/s, an exceptionally high rate among membrane-transport proteins. It is not known whether such rapid turnover is characteristic of ClCs in general or if the E. coli homologue represents a functional outlier. Here, we characterize a CLC Cl(-)/H(+) antiporter from the cyanobacterium Synechocystis sp. PCC6803 (SY) and determine its crystal structure at 3.2 A resolution. The structure of SY is nearly identical to that of EC, with all residues involved in Cl(-) binding and proton coupling structurally similar to their equivalents in EC. SY actively pumps protons into liposomes against a gradient and moves Cl(-) at approximately 20 s(-1), 1% of the EC rate. Electrostatic calculations, used to identify residues contributing to ion binding energetics in SY and EC, highlight two residues flanking the external binding site that are destabilizing for Cl(-) binding in SY and stabilizing in EC. Mutation of these two residues in SY to their counterparts in EC accelerates transport to approximately 150 s(-1), allowing measurement of Cl(-)/H(+) stoichiometry of 2/1. SY thus shares a similar structure and a common transport mechanism to EC, but it is by comparison slow, a result that refutes the idea that the transport mechanism of CLCs leads to intrinsically high rates.
| + | |
| - | | + | |
| - | Structure of a Slow CLC Cl(-)/H(+) Antiporter from a Cyanobacterium.,Jayaram H, Robertson JL, Wu F, Williams C, Miller C Biochemistry. 2011 Jan 11. PMID:21174448<ref>PMID:21174448</ref>
| + | |
| - | | + | |
| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
| + | |
| - | </div>
| + | |
| - | == References ==
| + | |
| - | <references/>
| + | |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Synechocystis]] | + | [[Category: Large Structures]] |
| - | [[Category: Jayaram, H]] | + | [[Category: Synechocystis sp. PCC 6803]] |
| - | [[Category: Miller, C]] | + | [[Category: Jayaram H]] |
| - | [[Category: Robertson, J]] | + | [[Category: Miller C]] |
| - | [[Category: Williams, C]] | + | [[Category: Robertson J]] |
| - | [[Category: Wu, F]] | + | [[Category: Williams C]] |
| - | [[Category: Clc family cl-/h+ antiporter]]
| + | [[Category: Wu F]] |
| - | [[Category: Clc_ec1 homolog]]
| + | |
| - | [[Category: P73745]]
| + | |
| - | [[Category: Synechocystis sp. pcc 6803]]
| + | |
| - | [[Category: Transport protein]]
| + | |
