1vgl

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[[Image:1vgl.gif|left|200px]]<br /><applet load="1vgl" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1vgl, resolution 2.6&Aring;" />
 
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'''Crystal structure of tetrameric KaiB from T.elongatus BP-1'''<br />
 
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==Overview==
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==Crystal structure of tetrameric KaiB from T.elongatus BP-1==
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KaiB is a component of the circadian clock oscillator in cyanobacteria, which are the simplest organisms that exhibit circadian rhythms. KaiB consists of 108 amino-acid residues and has a molecular weight of 12 025 Da. KaiB and Cys-substituted KaiB mutants from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 were expressed as GST-fusion proteins in Escherichia coli, purified and crystallized. The crystals of wild-type KaiB belong to the monoclinic space group P2(1), with unit-cell parameters a = 89.6, b = 71.2, c = 106.8 A, beta = 100.1 degrees. While the native crystals diffract to 3.7 A, osmium derivatives, which show an approximately 4 A shrinkage in the b axis, diffract to 2.6 A. The crystals of the singly Cys-substituted mutant T64C with Hg, which show different morphology, diffract to 2.5 A and belong to the monoclinic space group P2, with unit-cell parameters a = 63.7, b = 33.4, c = 93.7 A, beta = 100.1 degrees. Anomalous difference Patterson maps of the Os- and Hg-derivative crystals had significant peaks in their Harker sections, suggesting that both derivatives are suitable for structure determination.
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<StructureSection load='1vgl' size='340' side='right'caption='[[1vgl]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1vgl]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Thermosynechococcus_vestitus_BP-1 Thermosynechococcus vestitus BP-1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VGL OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1VGL FirstGlance]. <br>
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.6&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HG:MERCURY+(II)+ION'>HG</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1vgl FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1vgl OCA], [https://pdbe.org/1vgl PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1vgl RCSB], [https://www.ebi.ac.uk/pdbsum/1vgl PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1vgl ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/KAIB_THEVB KAIB_THEVB] Key component of the KaiABC oscillator complex, which constitutes the main circadian regulator in cyanobacteria (PubMed:24112939, PubMed:16227211, PubMed:28302851). Its composition changes during the circadian cycle to control KaiC phosphorylation. KaiA stimulates KaiC autophosphorylation, while KaiB sequesters KaiA, leading to KaiC autodephosphorylation. KaiA binding to KaiC yields KaiA(2-4):KaiC(6) complexes which stimulate KaiC autophosphorylation. Phospho-Ser-431 KaiC accumulation triggers binding of KaiB to form the KaiB(6):KaiC(6) complex, leading to changes in the output regulators CikA and SasA (PubMed:28302851). KaiB switches to a thioredoxin-like fold (KaiB(fs)) in complex with KaiC (PubMed:26113641, PubMed:28302851). KaiB(6):KaiC(6) formation exposes a site for KaiA binding that sequesters KaiA from the CII domain, making the KaiC(6):KaiB(6):KaiA(12) complex that results in KaiC autodephosphorylation. Complete dephosphorylation of KaiC leads to dissociation of KaiA(2):KaiB(1), completing 1 cycle of the Kai oscillator (PubMed:28302851).<ref>PMID:16227211</ref> <ref>PMID:24112939</ref> <ref>PMID:26113641</ref> <ref>PMID:28302851</ref> A metamorphic protein which reversibly switches between an inactive tetrameric fold and a rare, thioredoxin-like monomeric fold (KaiB(fs)). KaiB(fs) binds phospho-KaiC, KaiA and CikA. KaiA and CikA compete for binding to KaiB(fs), and KaiB(fs) and SasA compete for binding to KaiC, thus the clock oscillator and output signal pathway are tightly coupled.[HAMAP-Rule:MF_01835]<ref>PMID:26113641</ref> <ref>PMID:28302851</ref>
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/vg/1vgl_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1vgl ConSurf].
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<div style="clear:both"></div>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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KaiB is a component of the circadian clock molecular machinery in cyanobacteria, which are the simplest organisms that exhibit circadian rhythms. Here we report the x-ray crystal structure of KaiB from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1. The KaiB crystal diffracts at a resolution of 2.6 A and includes four subunits organized as a dimer of dimers, each composed of two non-equivalent subunits. The overall shape of the tetramer is an elongated hexagonal plate, with a single positively charged cleft flanked by two negatively charged ridges whose surfaces includes several terminal chains. Site-directed mutagenesis of Synechococcus KaiB confirmed that alanine substitution of residues Lys-11 or Lys-43 in the cleft, or deletion of C-terminal residues 95-108, which forms part of the ridges, strongly weakens in vivo circadian rhythms. Characteristics of KaiB deduced from the x-ray crystal structure were also confirmed by physicochemical measurements of KaiB in solution. These data suggest that the positively charged cleft and flanking negatively charged ridges in KaiB are essential for the biological function of KaiB in the circadian molecular machinery in cyanobacteria.
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==About this Structure==
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Functionally important substructures of circadian clock protein KaiB in a unique tetramer complex.,Iwase R, Imada K, Hayashi F, Uzumaki T, Morishita M, Onai K, Furukawa Y, Namba K, Ishiura M J Biol Chem. 2005 Dec 30;280(52):43141-9. Epub 2005 Oct 13. PMID:16227211<ref>PMID:16227211</ref>
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1VGL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteria Bacteria] with <scene name='pdbligand=HG:'>HG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VGL OCA].
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==Reference==
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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Crystallization and preliminary crystallographic analysis of the circadian clock protein KaiB from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1., Iwase R, Imada K, Hayashi F, Uzumaki T, Namba K, Ishiura M, Acta Crystallogr D Biol Crystallogr. 2004 Apr;60(Pt 4):727-9. Epub 2004, Mar 23. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15039567 15039567]
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</div>
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[[Category: Bacteria]]
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<div class="pdbe-citations 1vgl" style="background-color:#fffaf0;"></div>
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[[Category: Single protein]]
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[[Category: Hayashi, F.]]
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[[Category: Imada, K.]]
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[[Category: Ishiura, M.]]
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[[Category: Iwase, R.]]
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[[Category: Namba, K.]]
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[[Category: Uzumaki, T.]]
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[[Category: HG]]
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[[Category: circadian clock protein]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:35:02 2008''
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==See Also==
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*[[Circadian clock protein 3D structures|Circadian clock protein 3D structures]]
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== References ==
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<references/>
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__TOC__
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</StructureSection>
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[[Category: Large Structures]]
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[[Category: Thermosynechococcus vestitus BP-1]]
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[[Category: Hayashi F]]
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[[Category: Imada K]]
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[[Category: Ishiura M]]
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[[Category: Iwase R]]
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[[Category: Namba K]]
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[[Category: Uzumaki T]]

Current revision

Crystal structure of tetrameric KaiB from T.elongatus BP-1

PDB ID 1vgl

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