View source for 4knf


==Crystal structure of a blue-light absorbing proteorhodopsin double-mutant D97N/Q105L from HOT75==
<StructureSection load='4knf' size='340' side='right'caption='[[4knf]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4knf]] is a 5 chain structure with sequence from [http://en.wikipedia.org/wiki/Gamma_proteobacterium_'hot_75m4' Gamma proteobacterium 'hot 75m4']. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4KNF OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4KNF FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=RET:RETINAL'>RET</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4kly|4kly]], [[4jq6|4jq6]]</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=4knf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4knf OCA], [http://pdbe.org/4knf PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4knf RCSB], [http://www.ebi.ac.uk/pdbsum/4knf PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4knf ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/PRRB_PRB02 PRRB_PRB02]] Light-driven proton pump. May have a regulatory rather than energy harvesting function, based on light-induced opening of proton channels, to modulate cell physiology depending on light intensity variations. Could be, therefore, a sensory rhodopsin, potentially associated with a transducer component. 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Proteorhodopsins (PRs), members of the microbial rhodopsin superfamily of seven-transmembrane-helix proteins that use retinal chromophores, comprise the largest subfamily of rhodopsins, yet very little structural information is available. PRs are ubiquitous throughout the biosphere and their genes have been sequenced in numerous species of bacteria. They have been shown to exhibit ion-pumping activity like their archaeal homolog bacteriorhodopsin (BR). Here, the first crystal structure of a proteorhodopsin, that of a blue-light-absorbing proteorhodopsin (BPR) isolated from the Mediterranean Sea at a depth of 12 m (Med12BPR), is reported. Six molecules of Med12BPR form a doughnut-shaped C6 hexameric ring, unlike BR, which forms a trimer. Furthermore, the structures of two mutants of a related BPR isolated from the Pacific Ocean near Hawaii at a depth of 75 m (HOT75BPR), which show a C5 pentameric arrangement, are reported. In all three structures the retinal polyene chain is shifted towards helix C when compared with other microbial rhodopsins, and the putative proton-release group in BPR differs significantly from those of BR and xanthorhodopsin (XR). The most striking feature of proteorhodopsin is the position of the conserved active-site histidine (His75, also found in XR), which forms a hydrogen bond to the proton acceptor from the same molecule (Asp97) and also to Trp34 of a neighboring protomer. Trp34 may function by stabilizing His75 in a conformation that favors a deprotonated Asp97 in the dark state, and suggests cooperative behavior between protomers when the protein is in an oligomeric form. Mutation-induced alterations in proton transfers in the BPR photocycle in Escherichia coli cells provide evidence for a similar cross-protomer interaction of BPR in living cells and a functional role of the inter-protomer Trp34-His75 interaction in ion transport. Finally, Wat402, a key molecule responsible for proton translocation between the Schiff base and the proton acceptor in BR, appears to be absent in PR, suggesting that the ion-transfer mechanism may differ between PR and BR.

Cross-protomer interaction with the photoactive site in oligomeric proteorhodopsin complexes.,Ran T, Ozorowski G, Gao Y, Sineshchekov OA, Wang W, Spudich JL, Luecke H Acta Crystallogr D Biol Crystallogr. 2013 Oct;69(Pt 10):1965-80. doi:, 10.1107/S0907444913017575. Epub 2013 Sep 20. PMID:24100316<ref>PMID:24100316</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 4knf" style="background-color:#fffaf0;"></div>

==See Also==
*[[Bacteriorhodopsin 3D structures|Bacteriorhodopsin 3D structures]]
*[[Rhodopsin|Rhodopsin]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Gamma proteobacterium 'hot 75m4']]
[[Category: Large Structures]]
[[Category: Gao, Y]]
[[Category: Luecke, H]]
[[Category: Ozorowski, G]]
[[Category: Ran, T]]
[[Category: Wang, W]]
[[Category: Ion transport]]
[[Category: Membrane]]
[[Category: Proton pump]]
[[Category: Proton transport]]
[[Category: Retinylidene schiff base]]