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[[Image:1suy.jpg|left|200px]]<br /><applet load="1suy" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1suy" />
'''NMR structure of the ThKaiA180C-CIIABD complex (average minimized structure)'''<br />


==Overview==
==NMR structure of the ThKaiA180C-CIIABD complex (average minimized structure)==
Circadian clocks are widespread endogenous mechanisms that control the temporal pattern of diverse biological processes, including gene transcription. KaiA is the positive element of the cyanobacterial clock because KaiA overexpression elevates transcription levels of clock components. Recently, we showed that the structure of KaiA is that of a domain-swapped homodimer. The N-terminal domain is a pseudo-receiver; thus, it is likely to be involved in signal transduction in the clock-resetting pathway. The C-terminal domain of KaiA is structurally novel and enhances the KaiC autokinase activity directly. Here, we report the NMR structure of the C-terminal domain of KaiA (ThKaiA180C) in complex with a KaiC-derived peptide from the cyanobacterium Thermosynechococcus elongatus BP-1. The protein-peptide interface is revealed to be different from a model that was proposed earlier, is stabilized by a combination of hydrophobic and electrostatic interactions, and includes many residues known to produce a circadian-period phenotype upon substitution. Although the structure of the monomeric subunit of ThKaiA180C is largely unchanged upon peptide binding, the intersubunit dimerization angle changes. It is proposed that modulation of the C-terminal KaiA domain dimerization angle regulates KaiA-KaiC interactions.
<StructureSection load='1suy' size='340' side='right'caption='[[1suy]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1suy]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Thermosynechococcus_vestitus_BP-1 Thermosynechococcus vestitus BP-1]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SUY OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SUY FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</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=1suy FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1suy OCA], [https://pdbe.org/1suy PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1suy RCSB], [https://www.ebi.ac.uk/pdbsum/1suy PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1suy ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KAIA_THEVB KAIA_THEVB] Key component of the KaiABC oscillator complex, which constitutes the main circadian regulator in cyanobacteria. Complex 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 the KaiC CII domain during the subjective day yields KaiA(2-4):KaiC(6) complexes which stimulate KaiC autophosphorylation. Phospho-Ser-431 KaiC accumulation triggers binding of KaiB during the subjective night to form the KaiB(6):KaiC(6) complex, leading to changes in the output regulators CikA and SasA. KaiB(6):KaiC(6) formation exposes a site for KaiA binding on KaiB that sequesters KaiA from KaiC's CII domain, making the KaiC(6):KaiB(6):KaiA(12) complex resulting in KaiC autodephosphorylation. Complete dephosphorylation of KaiC leads to dissociation of KaiA(2):KaiB(1), completing 1 cycle of the Kai oscillator (By similarity). Formation of the KaiB:KaiC complex is promoted by KaiA, helping switch KaiC from its autophosphorylation to autodephosphatase function (PubMed:24112939).[UniProtKB:Q79PF6]<ref>PMID:24112939</ref>  Binds oxidized quinones via the N-terminal PsR domain, allowing it to sense redox changes and possibly mediate clock input.[UniProtKB:Q79PF6]
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/su/1suy_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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=1suy ConSurf].
<div style="clear:both"></div>


==About this Structure==
==See Also==
1SUY is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bacteria Bacteria]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SUY OCA].
*[[Circadian clock protein 3D structures|Circadian clock protein 3D structures]]
 
== References ==
==Reference==
<references/>
Structure of the C-terminal domain of the clock protein KaiA in complex with a KaiC-derived peptide: implications for KaiC regulation., Vakonakis I, LiWang AC, Proc Natl Acad Sci U S A. 2004 Jul 27;101(30):10925-30. Epub 2004 Jul 15. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15256595 15256595]
__TOC__
[[Category: Bacteria]]
</StructureSection>
[[Category: Protein complex]]
[[Category: Large Structures]]
[[Category: LiWang, A C.]]
[[Category: Thermosynechococcus vestitus BP-1]]
[[Category: Vakonakis, I.]]
[[Category: LiWang AC]]
[[Category: protein-peptide complex]]
[[Category: Vakonakis I]]
[[Category: x-class four helix bundle]]
 
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:05:26 2008''

Latest revision as of 11:35, 1 May 2024

NMR structure of the ThKaiA180C-CIIABD complex (average minimized structure)NMR structure of the ThKaiA180C-CIIABD complex (average minimized structure)

Structural highlights

1suy is a 4 chain structure with sequence from Thermosynechococcus vestitus BP-1. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:Solution NMR
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

KAIA_THEVB Key component of the KaiABC oscillator complex, which constitutes the main circadian regulator in cyanobacteria. Complex 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 the KaiC CII domain during the subjective day yields KaiA(2-4):KaiC(6) complexes which stimulate KaiC autophosphorylation. Phospho-Ser-431 KaiC accumulation triggers binding of KaiB during the subjective night to form the KaiB(6):KaiC(6) complex, leading to changes in the output regulators CikA and SasA. KaiB(6):KaiC(6) formation exposes a site for KaiA binding on KaiB that sequesters KaiA from KaiC's CII domain, making the KaiC(6):KaiB(6):KaiA(12) complex resulting in KaiC autodephosphorylation. Complete dephosphorylation of KaiC leads to dissociation of KaiA(2):KaiB(1), completing 1 cycle of the Kai oscillator (By similarity). Formation of the KaiB:KaiC complex is promoted by KaiA, helping switch KaiC from its autophosphorylation to autodephosphatase function (PubMed:24112939).[UniProtKB:Q79PF6][1] Binds oxidized quinones via the N-terminal PsR domain, allowing it to sense redox changes and possibly mediate clock input.[UniProtKB:Q79PF6]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

See Also

References

  1. ↑ Tseng R, Chang YG, Bravo I, Latham R, Chaudhary A, Kuo NW, Liwang A. Cooperative KaiA-KaiB-KaiC interactions affect KaiB/SasA competition in the circadian clock of cyanobacteria. J Mol Biol. 2014 Jan 23;426(2):389-402. PMID:24112939 doi:10.1016/j.jmb.2013.09.040
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