1wwj

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(New page: 200px<br /><applet load="1wwj" size="450" color="white" frame="true" align="right" spinBox="true" caption="1wwj, resolution 1.90&Aring;" /> '''crystal structure of...)
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Revision as of 03:35, 21 November 2007

Image:1wwj.gif

1wwj, resolution 1.90Å

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crystal structure of KaiB from Synechocystis sp.

Overview

Cyanobacteria are among the simplest organisms that show daily, rhythmicity. Their circadian rhythms consist of the localization, interaction, and accumulation of various proteins, including KaiA, KaiB, KaiC, and SasA. We have determined the 1.9-angstroms resolution, crystallographic structure of the cyanobacterial KaiB clock protein from, Synechocystis sp. PCC6803. This homotetrameric structure reveals a novel, KaiB interface for protein-protein interaction; the protruding hydrophobic, helix-turn-helix motif of one subunit fits into a groove between two, beta-strands of the adjacent subunit. A cyanobacterial mutant, in which, the Asp-Lys salt bridge mediating this tetramer-forming interaction is, disrupted by mutation of Asp to Gly, exhibits severely impaired, rhythmicity (a short free-running period; approximately 19 h). The KaiB, tetramer forms an open square, with positively charged residues around the, perimeter. KaiB is localized on the phospholipid-rich membrane and, translocates to the cytosol to interact with the other Kai components, KaiA and KaiC. KaiB antagonizes the action of KaiA on KaiC, and shares a, sequence-homologous domain with the SasA kinase. Based on our structure, we discuss functional roles for KaiB in the circadian clock.

About this Structure

1WWJ is a Single protein structure of sequence from Synechocystis sp. with MLT, IMD and BET as ligands. Full crystallographic information is available from OCA.

Reference

Tetrameric architecture of the circadian clock protein KaiB. A novel interface for intermolecular interactions and its impact on the circadian rhythm., Hitomi K, Oyama T, Han S, Arvai AS, Getzoff ED, J Biol Chem. 2005 May 13;280(19):19127-35. Epub 2005 Feb 16. PMID:15716274

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