>TIGR02655 circ_KaiC circadian clock protein KaiC; InterPro: IPR013503 The circadian clock protein KaiC, is encoded in the kaiABC operon that controls circadian rhythms and may be universal in Cyanobacteria. Each member contains two copies of the KaiC domain, which is also found in other proteins. KaiC performs autophosphorylation and acts as its own transcriptional repressor. Kai proteins (KaiA and KaiC) appear to positively and negatively regulate kaiBC transcription which is consistent with a transcription/translation oscillatory (TTO) feedback model, believed to be at the core of all self-sustained circadian timers. However, the cyanobacterial circadian clock is able to function without de novo synthesis of clock gene mRNAs and the clock proteins, and the period is accurately determined without TTO feedback and the system is also temperature-compensated. It has been demonstrated that these three purified proteins form a temperature-compensated molecular oscillator in vitro that exhibits rhythmic phosphorylation and dephosphorylation of KaiC. A negative-stain electron microscopy study of Synechococcus elongatus and Thermosynechococcus elongatus BP-1 KaiAKaiC complexes in combination with site-directed mutagenesis reveals that KaiA binds exclusively to the CII half of the KaiC hexamer. The EM-based model of the KaiAKaiC complex reveals proteinprotein interactions at two sites: the known interaction of the flexible C-terminal KaiC peptide with KaiA, and a second postulated interaction between the apical region of KaiA and the ATP binding cleft on KaiC. This model brings KaiA mutation sites that alter clock period or abolish rhythmicity into contact with KaiC and suggests how KaiA might regulate KaiC phosphorylation . ; GO: 0000287 magnesium ion binding, 0003677 DNA binding, 0004674 protein serine/threonine kinase activity, 0005524 ATP binding, 0042752 regulation of circadian rhythm, 0045449 regulation of transcription.

Probab=96.96  E-value=0.014  Score=39.08  Aligned_cols=76  Identities=25%  Similarity=0.396  Sum_probs=60.3

Q ss_pred             CCCCCHHHHHHH-HHHCCCCEEEEECCCHHHHHHHHHHHHHHHHHHCCCCCCCCCCCCCCCCCEEEEEECCCCHHHHHHH
Q ss_conf             432101377655-6416772677621310027699999999998510111233333212479758999585217999878
Q gi|254780332|r  202 VSTGIQTLDKQM-GGLQRSDLIIIAGRPGMGKTSLATNIAYNVADAYKAELQTDGSYKTINGGIVGFYSLEMSSEQLATR  280 (504)
Q Consensus       202 i~TG~~~LD~~~-gGl~~G~l~Viaarpg~GKTalalniA~~~A~~~~~~~~~~~~~~~~~g~~Vl~fSlEMs~~el~~R  280 (504)
T Consensus       245 vssGv~~ld~mCGGGff~dsiil~tGatGtGktllvs~f~~~~C~n---------------~~railfayeesraql~rn  309 (484)
T TIGR02655       245 VSSGVKRLDEMCGGGFFKDSIILATGATGTGKTLLVSKFLEDACKN---------------KERAILFAYEESRAQLLRN  309 (484)
T ss_pred             EHHHHHHHHHHCCCCEEEEEEEEEECCCCCCHHHHHHHHHHHHHCC---------------CCCEEEEEEHHHHHHHHHC
T ss_conf             1000466643217851210356762577766055666788864146---------------7735888511346777523


Q ss_pred             HHHHHHHHCCCCCC
Q ss_conf             99998741011000
Q gi|254780332|r  281 IISEQTEVPSSKIR  294 (504)
Q Consensus       281 ~is~~s~I~~~~i~  294 (504)
T Consensus       310 ~~s--WG~dfe~~e  321 (484)
T TIGR02655       310 AYS--WGIDFEELE  321 (484)
T ss_pred             CCC--CCCCHHHHC
T ss_conf             320--144378850