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==Carboxysome shell protein CcmP from Synechococcus elongatus PCC 7942==
<StructureSection load='5lt5' size='340' side='right'caption='[[5lt5]], [[Resolution|resolution]] 1.45&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5lt5]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Synechococcus_elongatus_PCC_7942_=_FACHB-805 Synechococcus elongatus PCC 7942 = FACHB-805]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5LT5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5LT5 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.45&#8491;</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>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene></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=5lt5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5lt5 OCA], [https://pdbe.org/5lt5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5lt5 RCSB], [https://www.ebi.ac.uk/pdbsum/5lt5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5lt5 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CCMP_SYNE7 CCMP_SYNE7] Probably part of the carboxysome shell, a polyhedral inclusion where RuBisCO (ribulose bisphosphate carboxylase, rbcL-rbcS) is sequestered. It is thought that this protein controls transport of RuBisCO reactants in and out of the carboxysome; residual densities in the 4 X-ray structures suggest that differing compounds bind in interior pockets, depending on the open or closed state of the pore.<ref>PMID:23572529</ref> 
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== Publication Abstract from PubMed ==
Cyanobacterial CO2 fixation is promoted by encapsulating and co-localizing the CO2-fixing enzymes within a protein shell, the carboxysome. A key feature of the carboxysome is its ability to control selectively the flux of metabolites in and out of the shell. The beta-carboxysome shell protein CcmP has been shown to form a double layer of pseudohexamers with a relatively large central pore (~13 A diameter), which may allow passage of larger metabolites such as the substrate for CO2 fixation, ribulose 1,5-bisphosphate, through the shell. Here we describe two crystal structures, at 1.45 A and 1.65 A resolution, of CcmP from Synechococcus elongatus PCC7942 (SeCcmP). The central pore of CcmP is open or closed at its ends, depending on the conformation of two conserved residues, Glu69 and Arg70. The presence of glycerol resulted in a pore that is open at one end and closed at the opposite end. When glycerol was omitted, both ends of the barrel became closed. A binding pocket at the interior of the barrel featured residual density with distinct differences in size and shape depending on the conformation, open or closed, of the central pore of SeCcmP, suggestive of a metabolite-driven mechanism for the gating of the pore.

Crystal structures of beta-carboxysome shell protein CcmP: ligand binding correlates with the closed or open central pore.,Larsson AM, Hasse D, Valegard K, Andersson I J Exp Bot. 2017 Mar 28. doi: 10.1093/jxb/erx070. PMID:28369612<ref>PMID:28369612</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 5lt5" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Synechococcus elongatus PCC 7942 = FACHB-805]]
[[Category: Andersson I]]
[[Category: Hasse D]]
[[Category: Larsson AM]]
[[Category: Valegard K]]