ID   KAIA_SYNY3              Reviewed;         299 AA.
AC   P74644;
DT   11-OCT-2004, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1997, sequence version 1.
DT   25-MAY-2022, entry version 105.
DE   RecName: Full=Circadian clock protein KaiA;
GN   Name=kaiA; OrderedLocusNames=slr0756;
OS   Synechocystis sp. (strain PCC 6803 / Kazusa).
OC   Bacteria; Cyanobacteria; Synechococcales; Merismopediaceae; Synechocystis;
OC   unclassified Synechocystis.
OX   NCBI_TaxID=1111708;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=PCC 6803 / Kazusa;
RX   PubMed=8905231; DOI=10.1093/dnares/3.3.109;
RA   Kaneko T., Sato S., Kotani H., Tanaka A., Asamizu E., Nakamura Y.,
RA   Miyajima N., Hirosawa M., Sugiura M., Sasamoto S., Kimura T., Hosouchi T.,
RA   Matsuno A., Muraki A., Nakazaki N., Naruo K., Okumura S., Shimpo S.,
RA   Takeuchi C., Wada T., Watanabe A., Yamada M., Yasuda M., Tabata S.;
RT   "Sequence analysis of the genome of the unicellular cyanobacterium
RT   Synechocystis sp. strain PCC6803. II. Sequence determination of the entire
RT   genome and assignment of potential protein-coding regions.";
RL   DNA Res. 3:109-136(1996).
CC   -!- FUNCTION: Component of the KaiABC clock protein complex, which
CC       constitutes the main circadian regulator in cyanobacteria. The KaiABC
CC       complex may act as a promoter-nonspecific transcription regulator that
CC       represses transcription, possibly by acting on the state of chromosome
CC       compaction. In the complex, it enhances the phosphorylation status of
CC       KaiC. In contrast, the presence of KaiB in the complex decreases the
CC       phosphorylation status of KaiC, suggesting that KaiB acts by
CC       antagonizing the interaction between KaiA and KaiC. A KaiA dimer is
CC       sufficient to enhance KaiC hexamer phosphorylation (By similarity).
CC       {ECO:0000250}.
CC   -!- SUBUNIT: Homodimer. Component of the KaiABC complex, at least composed
CC       of a KaiC homohexamer, a KaiB dimer and two KaiA dimers. The KaiABC
CC       complex also interacts with SasA (By similarity). {ECO:0000250}.
CC   -!- DOMAIN: The KaiA domain mediates the interaction with KaiC, the
CC       homodimerization, and is responsible for the clock oscillation
CC       function. {ECO:0000250}.
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DR   EMBL; BA000022; BAA18760.1; -; Genomic_DNA.
DR   PIR; S76848; S76848.
DR   AlphaFoldDB; P74644; -.
DR   SMR; P74644; -.
DR   STRING; 1148.1653850; -.
DR   PaxDb; P74644; -.
DR   EnsemblBacteria; BAA18760; BAA18760; BAA18760.
DR   KEGG; syn:slr0756; -.
DR   eggNOG; ENOG502Z8HQ; Bacteria.
DR   OMA; VMAHLCE; -.
DR   Proteomes; UP000001425; Chromosome.
DR   GO; GO:0007623; P:circadian rhythm; TAS:UniProtKB.
DR   GO; GO:0006468; P:protein phosphorylation; IEA:InterPro.
DR   Gene3D; 1.10.1240.30; -; 1.
DR   InterPro; IPR011006; CheY-like_superfamily.
DR   InterPro; IPR011648; Circadian_clock_KaiA.
DR   InterPro; IPR020844; Circadian_clock_KaiA_N.
DR   InterPro; IPR020856; Circadian_clock_protein_KaiA_C.
DR   InterPro; IPR017944; KaiA/RbsU_helical_domain_sf.
DR   Pfam; PF07688; KaiA; 1.
DR   SMART; SM01247; KaiA; 1.
DR   SUPFAM; SSF101215; SSF101215; 1.
DR   SUPFAM; SSF52172; SSF52172; 1.
DR   PROSITE; PS51431; KAIA_C; 1.
DR   PROSITE; PS51430; KAIA_N; 1.
PE   3: Inferred from homology;
KW   Biological rhythms; Reference proteome.
FT   CHAIN           1..299
FT                   /note="Circadian clock protein KaiA"
FT                   /id="PRO_0000217874"
FT   DOMAIN          1..169
FT                   /note="KaiA N-terminal"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00760"
FT   DOMAIN          179..287
FT                   /note="KaiA C-terminal"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00761"
SQ   SEQUENCE   299 AA;  34894 MW;  D92BBD5BB921F2CC CRC64;
     MQSPLSLCLF APEHVAHRLR SIFQGDRHYL STFQALDDFC AFLEDKPERI DCLLVYYEAN
     SLPVLNRLYE QGRLLPIILL EPSPSALAKT TDEHPTIVYH NAEIHLPESQ WSELPTVVDR
     AIAHYLHLGP ICTLPNQTET IPAPIVDESS QSFLLLQQRR LADKLKERLG YLGVYYKRKP
     SHFYRNFSPQ EKQEYLEDLS SQYREIILSY FSDEGTVNDL LDQFVNQAFF ADLAISQILE
     IHMELMDEFS QHLKLEGRSE EVLLDYRLVL IDILAHLGEM YRRSIPREDI PFDVYYQTD