>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=99.30 E-value=2.5e-12 Score=109.53 Aligned_cols=200 Identities=27% Similarity=0.385 Sum_probs=156.2 Q ss_pred CCCCCCCCCCCCHHHHHHHCCCCCCCCEEEEECCCCCCHHHHHHHHHHHHHCCCCCEEEEECCCCHHHHHHHHHHCCCCC Q ss_conf 45566632378124888865985787089995498751889999999998503981999986463047888875201577 Q gi|254780334|r 65 SIEEESRIQTHIDELDRVTGGGFVRGSVILVGGDPGIGKSTLLMQTAASLAYKKHRITYVSGEEAIGQIRLRAQRLNTIN 144 (479) Q Consensus 65 ~~~~~~Ri~TGi~eLDrvLGGGl~~Gs~~Li~G~PGvGKSTL~Lqia~~~a~~g~~vlYvS~EEs~~Qi~~Ra~Rl~~~~ 144 (479) T Consensus 238 qrssn~rvssGv~~ld~mCGGGff~dsiil~tGatGtGktllvs~f~~~~C~n~~railfayeesraql~rn~~sWG~df 317 (484) T TIGR02655 238 QRSSNVRVSSGVKRLDEMCGGGFFKDSIILATGATGTGKTLLVSKFLEDACKNKERAILFAYEESRAQLLRNAYSWGIDF 317 (484) T ss_pred HCCCCCEEHHHHHHHHHHCCCCEEEEEEEEEECCCCCCHHHHHHHHHHHHHCCCCCEEEEEEHHHHHHHHHCCCCCCCCH T ss_conf 10024021000466643217851210356762577766055666788864146773588851134677752332014437 Q ss_pred CCHH------E---ECC-CCHHHH---HHHHHHCCCCCEEEECHHHHHHHHHHCCCCCCHHHHHHHHHHHHHHHHHCCCE Q ss_conf 5100------0---034-788999---99997316982899721687665420445563679999999999975307978 Q gi|254780334|r 145 SSVY------I---AIE-TNVEDI---IATLITNEKPDLVIIDSIQTLWSQTAESSPGTVIQVRTSVQAMIQYAKKNGVA 211 (479) Q Consensus 145 ~~i~------~---~~e-~~l~~i---l~~~i~~~~~~~vVIDSIQtl~~~~~~s~~GsvsQvre~~~~L~~~AK~~~i~ 211 (479) T Consensus 318 e~~e~~~llki~C~yPes~Gledhlq~ik~~i~~fkP~r~~idslsalarGvs~n------afrqfviGvtGyakqeei~ 391 (484) T TIGR02655 318 EELEQQGLLKIICAYPESAGLEDHLQIIKSEIAEFKPARIAIDSLSALARGVSNN------AFRQFVIGVTGYAKQEEIT 391 (484) T ss_pred HHHCCCCCEEEEEECCCCCCHHHHHHHHHHHHHHCCCCHHHHHHHHHHHHHHHHH------HHEEEEEEECCCCCHHHCE T ss_conf 8850037237777077746617899999877742385300156577775321221------0003356411311200100 Q ss_pred EEEEEEECCCCCCCCHHHH-----HHHHHEEE---EEECCCCCCCCCCEEEEEEEECCCCCCCEEE--EEECCCCCE Q ss_conf 9998630366543311457-----87753027---8515556665442156763202567651279--985156631 Q gi|254780334|r 212 MVLVGHVTKEGQIAGPRVI-----EHMVDAVL---YFEGGTRNTQYDYRILRSVKNRFGPTDEIGV--FEMSDKGLQ 278 (479) Q Consensus 212 vilighvTK~G~iAGp~~L-----eH~VD~vl---~~ege~~~~~~~~R~Lr~~KNRfG~t~e~gv--f~m~~~Gl~ 278 (479) T Consensus 392 G~ftn---t~~~f~G~hsit~shistitdtil~lqyve----i~Gem~ra~nvfkmr-GsWhdk~ire~~i~~~GP~ 460 (484) T TIGR02655 392 GFFTN---TSDQFLGSHSITDSHISTITDTILLLQYVE----IRGEMSRAINVFKMR-GSWHDKGIREYVISDKGPE 460 (484) T ss_pred EEEEC---CHHHHCCCCCCCHHHHHHHHHHHHHHHHHH----HHHHHHHHHHHHHCC-CCCCCCCEEEEEECCCCCH T ss_conf 22202---301230220000003567888887777765----533355443222002-5411253135664167832

HHsearch alignment for GI: 254780334 and conserved domain: TIGR02655