1r5p
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Revision as of 19:49, 26 May 2008
Crystal Structure Analysis of KaiB from PCC7120
Overview
The cyanobacterial clock proteins KaiA and KaiB are proposed as regulators of the circadian rhythm in cyanobacteria. Mutations in both proteins have been reported to alter or abolish circadian rhythmicity. Here, we present molecular models of both KaiA and KaiB from the cyanobacteria Anabaena sp PCC7120 deduced by crystal structure analysis, and we discuss how clock-changing or abolishing mutations may cause their resulting circadian phenotype. The overall fold of the KaiA monomer is that of a four-helix bundle. KaiB, on the other hand, adopts an alpha-beta meander motif. Both proteins purify and crystallize as dimers. While the folds of the two proteins are clearly different, their size and some surface features of the physiologically relevant dimers are very similar. Notably, the functionally relevant residues Arg 69 of KaiA and Arg 23 of KaiB align well in space. The apparent structural similarities suggest that KaiA and KaiB may compete for a potential common binding site on KaiC.
About this Structure
1R5P is a Single protein structure of sequence from Anabaena sp.. Full crystallographic information is available from OCA.
Reference
Anabaena circadian clock proteins KaiA and KaiB reveal a potential common binding site to their partner KaiC., Garces RG, Wu N, Gillon W, Pai EF, EMBO J. 2004 Apr 21;23(8):1688-98. Epub 2004 Apr 8. PMID:15071498 Page seeded by OCA on Mon May 26 22:49:53 2008
