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HAMAP rule MF_01836

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General rule information [?]

Accession MF_01836
Dates 13-SEP-2004 (Created)
1-JUN-2023 (Last updated, Version 28)
Name KaiC
Scope(s) Bacteria
Cyanobacteriota
Template(s) Q79PF4 (KAIC_SYNE7); Q79V60 (KAIC_THEVB); P74646 (KAIC1_SYNY3); Q7V0C4 (KAIC_PROMP); [ Recover all ]
Triggered by HAMAP; MF_01836 (Get profile general information and statistics)

Propagated annotation [?]

Identifier, protein and gene names [?]

Identifier KAIC
Protein name RecName: Full=Circadian clock oscillator protein KaiC;
                 EC=2.7.11.1;
                 EC=3.6.4.-;
Gene name Name=kaiC;

Comments [?]

case not <OC:Prochlorococcus>
FUNCTIONCentral component of the KaiABC oscillator complex, which constitutes the main circadian regulator in cyanobacteria. Complex composition changes during the circadian cycle to control KaiC phosphorylation. KaiA stimulates KaiC autophosphorylation, while KaiB sequesters KaiA, leading to KaiC autodephosphorylation. Clock output pathways impact the RpaA transcriptional regulator. KaiC enhances the autophosphorylation activity of SasA, which then transfers its phosphate group to RpaA to activate it. KaiB and KaiC together enhance the phospho-RpaA dephosphatase activity of CikA.
FUNCTIONHas a weak, temperature-independent ATPase activity; ATPase activity defines the circadian period. The phosphorylation state of KaiC modulates its ATPase activity and effects KaiB binding.
CATALYTIC ACTIVITY Reaction=ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl- [protein]; Xref=Rhea:RHEA:17989, Rhea:RHEA-COMP:9863, Rhea:RHEA- COMP:11604, ChEBI:CHEBI:15378, ChEBI:CHEBI:29999, ChEBI:CHEBI:30616, ChEBI:CHEBI:83421, ChEBI:CHEBI:456216; EC=2.7.11.1;
CATALYTIC ACTIVITY Reaction=ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L- threonyl-[protein]; Xref=Rhea:RHEA:46608, Rhea:RHEA-COMP:11060, Rhea:RHEA-COMP:11605, ChEBI:CHEBI:15378, ChEBI:CHEBI:30013, ChEBI:CHEBI:30616, ChEBI:CHEBI:61977, ChEBI:CHEBI:456216; EC=2.7.11.1;
CATALYTIC ACTIVITY Reaction=ATP + H2O = ADP + H(+) + phosphate; Xref=Rhea:RHEA:13065, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:30616, ChEBI:CHEBI:43474, ChEBI:CHEBI:456216;
COFACTOR Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Note=Binds 2 Mg(2+) ions per subunit, one in each domain. Mg(2+) is required for hexamerization and phosphatase activity.
ACTIVITY REGULATIONThe interaction with KaiA enhances its phosphorylation status, while the interaction with KaiB decreases it.
SUBUNITHomohexamer; hexamerization is dependent on ATP-binding. The KaiABC complex composition changes during the circadian cycle to control KaiC phosphorylation. Complexes KaiC(6), KaiA(2-4):KaiC(6), KaiB(6):KaiC(6) and KaiC(6):KaiB(6):KaiA(12) are among the most important forms, many form cooperatively. KaiC interacts with SasA, activating its autokinase function and leading to RpaA activation.
DOMAINIn the homohexamer the 2 domains (called CI and CII) self- associate to each form a 'donut' layer; the compactness and local conformation of the domains varies over the cell cycle and impacts function. CII has the autokinase and autophosphatase activities, both CI and CII have (weak) ATPase activity; CI has the clock pacemaker role.
PTMPhosphorylated on serine and threonine residues by autocatalysis. Has a 4 step phosphorylation cycle; the autokinase acts first on #{Thr- 432}, then #{Ser-431}. When #{Ser-431} is modified KaiC switches to an autophosphatase mode, acting first on phospho-#{Thr-432} then phospho-#{Ser-431}.
end case
case <OC:Prochlorococcus>
FUNCTIONCentral component of the KaiBC oscillator complex, which constitutes the main circadian regulator in cyanobacteria. Its composition changes during the circadian cycle to control KaiC phosphorylation. Autophosphorylates and has a weak ATPase activity; ATPase activity defines the circadian period.
CATALYTIC ACTIVITY Reaction=ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl- [protein]; Xref=Rhea:RHEA:17989, Rhea:RHEA-COMP:9863, Rhea:RHEA- COMP:11604, ChEBI:CHEBI:15378, ChEBI:CHEBI:29999, ChEBI:CHEBI:30616, ChEBI:CHEBI:83421, ChEBI:CHEBI:456216; EC=2.7.11.1;
CATALYTIC ACTIVITY Reaction=ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L- threonyl-[protein]; Xref=Rhea:RHEA:46608, Rhea:RHEA-COMP:11060, Rhea:RHEA-COMP:11605, ChEBI:CHEBI:15378, ChEBI:CHEBI:30013, ChEBI:CHEBI:30616, ChEBI:CHEBI:61977, ChEBI:CHEBI:456216; EC=2.7.11.1;
CATALYTIC ACTIVITY Reaction=ATP + H2O = ADP + H(+) + phosphate; Xref=Rhea:RHEA:13065, ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:30616, ChEBI:CHEBI:43474, ChEBI:CHEBI:456216;
COFACTOR Name=Mg(2+); Xref=ChEBI:CHEBI:18420; Note=Binds 2 Mg(2+) ions per subunit, one in each domain. Mg(2+) is required for hexamerization and phosphatase activity.
SUBUNITHomohexamer; hexamerization is dependent on ATP-binding. Component of the KaiBC complex. KaiC interacts with SasA, activating its autokinase function and leading to RpaA activation.
DOMAINIn the homohexamer the 2 domains (called CI and CII) self- associate to each form a 'donut' layer; the compactness and local conformation of the domains varies over the cell cycle and impacts function. CII has the autokinase and autophosphatase activities, both CI and CII have (weak) ATPase activity; CI has the clock pacemaker role.
PTMPhosphorylated on serine and threonine residues by autocatalysis. Has a 4 step phosphorylation cycle; the autokinase acts first on #{Thr- 432}, then #{Ser-431}. When #{Ser-431} is modified KaiC switches to an autophosphatase mode, acting first on phospho-#{Thr-432} then phospho-#{Ser-431}.
MISCELLANEOUSThe kiaA gene has been eliminated from Prochlorococcus during genome streamlining. It has been suggested that the central oscillator in Prochlorococcus does not have to be as robust as in other cyanobacteria because the former live in specific niches of the Earth's oceans; they divide exactly once a day and at the same time. Thus gene loss, and changes in kaiC function compared to other cyanobacteria, can occur.
end case
SIMILARITYBelongs to the KaiC family.

Keywords [?]

ATP-binding
Nucleotide-binding
Biological rhythms
Hydrolase
Magnesium
Metal-binding
case <FTTag:phospho>
Phosphoprotein
end case
Repeat
Repressor
Kinase
Serine/threonine-protein kinase
Transcription
Transcription regulation
Transferase

Gene Ontology [?]

GO:0000287; Molecular function:magnesium ion binding
GO:0004712; Molecular function:protein serine/threonine/tyrosine kinase activity
GO:0005524; Molecular function:ATP binding
GO:0007623; Biological process:circadian rhythm

Cross-references [?]

PROSITE PS51146; KAIC; 2;
Pfam PF06745; KaiC; 1;
NCBIfam TIGR02655; circ_KaiC; 1;

Features [?]

From: KAIC_SYNE7 (Q79PF4)
Key From To Description Tag Condition FTGroup
DOMAIN 1 247 /note="KaiC 1"
DOMAIN 261 Cter /note="KaiC 2"
BINDING 49 49 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 G
BINDING 50 50 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 51 51 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 G
BINDING 52 52 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 K
BINDING 53 53 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 53 53 /ligand="Mg(2+)"
/ligand_id="ChEBI:CHEBI:18420"
/ligand_label="1"		 T
BINDING 54 54 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 L
BINDING 89 89 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 S
BINDING 224 224 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 K
BINDING 225 225 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 L
BINDING 226 226 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 R
BINDING 228 228 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 230 230 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 H
BINDING 240 240 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 241 241 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="1"
/ligand_note="ligand shared between homodimeric partners"		 D
BINDING 290 290 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 291 291 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 G
BINDING 292 292 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 293 293 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 G
BINDING 294 294 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 K
BINDING 295 295 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 T
BINDING 295 295 /ligand="Mg(2+)"
/ligand_id="ChEBI:CHEBI:18420"
/ligand_label="2"		 T
BINDING 296 296 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 L
BINDING 318 318 /ligand="Mg(2+)"
/ligand_id="ChEBI:CHEBI:18420"
/ligand_label="2"		 E
BINDING 331 331 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 W
BINDING 451 451 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 R
BINDING 457 457 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 K
BINDING 458 458 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 M
BINDING 459 459 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 R
BINDING 461 461 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 S
BINDING 463 463 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 H
BINDING 465 465 /ligand="ATP"
/ligand_id="ChEBI:CHEBI:30616"
/ligand_label="2"
/ligand_note="ligand shared between homodimeric partners"		 K
MOD_RES 431 431 /note="Phosphoserine; by autocatalysis" phospho S
MOD_RES 432 432 /note="Phosphothreonine; by autocatalysis" phospho T

Additional information [?]

Size range 499-541 amino acids
Related rules None
Fusion Nter: None Cter: None
Comments Prochlorococcus do not contain KaiA (which stimulates KaiC autophosphorylation activity), suggesting that regulation of circadian cycle is different in these bacteria.



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