1VGL
Crystal structure of tetrameric KaiB from T.elongatus BP-1
Summary for 1VGL
| Entry DOI | 10.2210/pdb1vgl/pdb |
| Descriptor | Circadian clock protein kaiB, MERCURY (II) ION (3 entities in total) |
| Functional Keywords | circadian clock protein |
| Biological source | Thermosynechococcus elongatus BP-1 |
| Total number of polymer chains | 4 |
| Total formula weight | 48569.52 |
| Authors | Iwase, R.,Imada, K.,Hayashi, F.,Uzumaki, T.,Namba, K.,Ishiura, M. (deposition date: 2004-04-27, release date: 2005-08-16, Last modification date: 2023-12-27) |
| Primary citation | Iwase, R.,Imada, K.,Hayashi, F.,Uzumaki, T.,Morishita, M.,Onai, K.,Furukawa, Y.,Namba, K.,Ishiura, M. Functionally important substructures of circadian clock protein KaiB in a unique tetramer complex. J.Biol.Chem., 280:43141-43149, 2005 Cited by PubMed Abstract: 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. PubMed: 16227211DOI: 10.1074/jbc.M503360200 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.6 Å) |
Structure validation
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