Q06904 · SASA_SYNE7
- ProteinAdaptive-response sensory kinase SasA
- GenesasA
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids387 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Member of the two-component regulatory system SasA/RpaA involved in genome-wide circadian gene expression (PubMed:16882723).
One of three clock output pathways. Participates in the KaiABC clock protein complex, which constitutes the main circadian regulator in cyanobacteria, via its interaction with KaiC. Required for robustness of the circadian rhythm of gene expression and involved in clock output (PubMed:10786837, PubMed:20133618, PubMed:34618577).
KaiC enhances the autophosphorylation activity of SasA, which then transfers its phosphate group to RpaA to activate it. Phosphotransfer is maximal when KaiC phosphorylation is active during the circadian cycle; this two-component system is activated by fully phosphorylated KaiC (PubMed:16707582, PubMed:16882723, PubMed:23541768, PubMed:26113641, PubMed:34618577).
A very robust clock is reconstituted with KaiA, KaiB, KaiC, SasA, CikA and RpaA; output is measured by transcription from an appropriate reporter (PubMed:34618577).
In addition to its output function, recruits fold-shifted KaiB (KaiB(fs)) to KaiC to cooperatively form the KaiB6:KaiC6 complex (independent of SasA kinase activity); at physiological concentrations increases their association. At higher concentrations SasA and KaiB(fs) compete to bind to KaiC. Mutations that decrease cooperativity nearly phenocopy a deletion mutation (PubMed:34618577).
One of three clock output pathways. Participates in the KaiABC clock protein complex, which constitutes the main circadian regulator in cyanobacteria, via its interaction with KaiC. Required for robustness of the circadian rhythm of gene expression and involved in clock output (PubMed:10786837, PubMed:20133618, PubMed:34618577).
KaiC enhances the autophosphorylation activity of SasA, which then transfers its phosphate group to RpaA to activate it. Phosphotransfer is maximal when KaiC phosphorylation is active during the circadian cycle; this two-component system is activated by fully phosphorylated KaiC (PubMed:16707582, PubMed:16882723, PubMed:23541768, PubMed:26113641, PubMed:34618577).
A very robust clock is reconstituted with KaiA, KaiB, KaiC, SasA, CikA and RpaA; output is measured by transcription from an appropriate reporter (PubMed:34618577).
In addition to its output function, recruits fold-shifted KaiB (KaiB(fs)) to KaiC to cooperatively form the KaiB6:KaiC6 complex (independent of SasA kinase activity); at physiological concentrations increases their association. At higher concentrations SasA and KaiB(fs) compete to bind to KaiC. Mutations that decrease cooperativity nearly phenocopy a deletion mutation (PubMed:34618577).
Autophosphorylation and phosphotransfer activities are not essential for clock rhythms in continuous light, but they are essential for adaptation to light/dark cycles.
Catalytic activity
GO annotations
Aspect | Term | |
---|---|---|
Molecular Function | ATP binding | |
Molecular Function | phosphorelay sensor kinase activity | |
Biological Process | circadian regulation of translation | |
Biological Process | circadian rhythm |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameAdaptive-response sensory kinase SasA
- EC number
- Alternative names
Gene names
Organism names
- Strain
- Taxonomic lineageBacteria > Cyanobacteriota > Cyanophyceae > Synechococcales > Synechococcaceae > Synechococcus
Accessions
- Primary accessionQ06904
- Secondary accessions
Proteomes
Phenotypes & Variants
Disruption phenotype
No growth phenotype in low, continuous light, dysregulation of expression of many genes. In a light/dark regime cells grow very slowly (PubMed:10786837, PubMed:20133618, PubMed:22512339).
At medium light lowers kaiA and kaiBC expression, attenuating but not destroying circadian rhythms and affecting the expression of many genes (clock output) (PubMed:10786837, PubMed:20133618).
Chromosome compaction remains rhythmic (PubMed:16707582).
Loss of circadian control of gene expression; KaiA protein levels are unaffected, KaiC is constitutively phosphorylated (PubMed:16882723).
Phospho-RpaA is barely detected (PubMed:23541768).
At medium light lowers kaiA and kaiBC expression, attenuating but not destroying circadian rhythms and affecting the expression of many genes (clock output) (PubMed:10786837, PubMed:20133618).
Chromosome compaction remains rhythmic (PubMed:16707582).
Loss of circadian control of gene expression; KaiA protein levels are unaffected, KaiC is constitutively phosphorylated (PubMed:16882723).
Phospho-RpaA is barely detected (PubMed:23541768).
Features
Showing features for mutagenesis.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Mutagenesis | 28 | Decreases KaiB-KaiC complex cooperativity. More severe decrease; when associated with A-94, double mutant binds KaiC and phosphorylates RpaA. | ||||
Sequence: H → A | ||||||
Mutagenesis | 94 | Decreases KaiB-KaiC complex cooperativity. More severe decrease; when associated with A-28, double mutant binds KaiC and phosphorylates RpaA. | ||||
Sequence: Q → A | ||||||
Mutagenesis | 161 | No change in stimulation of KaiB-KaiC complex cooperativity, probably catalytically inactive. Period length increases by 2 hours, impaired growth in light/dark cycle at 30 and 42 umol/m2/sec photons. | ||||
Sequence: H → A | ||||||
Mutagenesis | 161 | Period length increases by 2 hours, impaired growth in light/dark cycle at 30 and 42 umol/m2/sec photons. | ||||
Sequence: H → D or E | ||||||
Mutagenesis | 161 | Lowers the amplitude of circadian rhythm, similar to disruption. | ||||
Sequence: H → Q |
PTM/Processing
Features
Showing features for chain, modified residue.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Chain | PRO_0000074872 | 1-387 | Adaptive-response sensory kinase SasA | |||
Sequence: MGESLSPQALAQPLLLQLFVDTRPLSQHIVQRVKNILAAVEATVPISLQVINVADQPQLVEYYRLVVTPALVKIGPGSRQVLSGIDLTDQLANQLPQWLVQQEAFFADREPPEVNIPFTELGQPETPALQQADAFFQLQQQYADLSERTKFLEQVIALVAHDLRNPLTAALLAVDTIQIRSQSFSVATAKEMQGLCSLFDQARSQLREIERMIAEILEATRHSGESLRINPREVVFEPLLQQVLEQLHERWRSKQQQLITDVPGDLPTLYADPDRLRQVLVNLLDNAIKYTPPGGTITIAALHRTSQKVQISISDTGSGIPRDQLSVIFKNLVRLSRDSSQEGYGIGLSVCQRIVQAHFGRIWVASELGQGSTFHFTMPVYRYTMPC | ||||||
Modified residue | 161 | Phosphohistidine; by autocatalysis | ||||
Sequence: H |
Post-translational modification
Autophosphorylates in vitro.
Keywords
- PTM
Proteomic databases
Expression
Induction
Transcribed in a circadian pattern, protein accumulates in light (at protein level).
Interaction
Subunit
Homooligomerizes (By similarity).
Part of the circadian clock (KaiA, KaiB, KaiC, CikA, RpaA, SasA), the composition of which varies during the circadian cycle (PubMed:10786837, PubMed:15347812, PubMed:26113641, PubMed:28302851, PubMed:34618577).
Binds to the CI domain of KaiC; KaiB(fs) and SasA compete for the binding site (PubMed:10786837, PubMed:15347812, PubMed:26113641, PubMed:28302851, PubMed:34618577).
Binds preferentially to doubly phosphorylated KaiC (PubMed:34618577).
Interacts with LdpA (PubMed:15775978).
Part of the circadian clock (KaiA, KaiB, KaiC, CikA, RpaA, SasA), the composition of which varies during the circadian cycle (PubMed:10786837, PubMed:15347812, PubMed:26113641, PubMed:28302851, PubMed:34618577).
Binds to the CI domain of KaiC; KaiB(fs) and SasA compete for the binding site (PubMed:10786837, PubMed:15347812, PubMed:26113641, PubMed:28302851, PubMed:34618577).
Binds preferentially to doubly phosphorylated KaiC (PubMed:34618577).
Interacts with LdpA (PubMed:15775978).
Binary interactions
Type | Entry 1 | Entry 2 | Number of experiments | Intact | |
---|---|---|---|---|---|
BINARY | Q06904 | kaiC Q79PF4 | 6 | EBI-626872, EBI-592287 |
Protein-protein interaction databases
Structure
Family & Domains
Features
Showing features for region, domain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Region | 1-97 | Interacts with KaiC | ||||
Sequence: MGESLSPQALAQPLLLQLFVDTRPLSQHIVQRVKNILAAVEATVPISLQVINVADQPQLVEYYRLVVTPALVKIGPGSRQVLSGIDLTDQLANQLPQ | ||||||
Domain | 158-382 | Histidine kinase | ||||
Sequence: LVAHDLRNPLTAALLAVDTIQIRSQSFSVATAKEMQGLCSLFDQARSQLREIERMIAEILEATRHSGESLRINPREVVFEPLLQQVLEQLHERWRSKQQQLITDVPGDLPTLYADPDRLRQVLVNLLDNAIKYTPPGGTITIAALHRTSQKVQISISDTGSGIPRDQLSVIFKNLVRLSRDSSQEGYGIGLSVCQRIVQAHFGRIWVASELGQGSTFHFTMPVYR |
Domain
The N-terminus interacts with KaiC, while the C-terminal histidine kinase domain autophosphorylates and is probably responsible for self-oligomerization. The N-terminal domain stimulates the C-terminus to autophosphorylate.
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Length387
- Mass (Da)43,315
- Last updated2006-04-18 v2
- Checksum04A0A097C3EE0438
Features
Showing features for sequence conflict.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Sequence conflict | 135 | in Ref. 1; BAA03145 | ||||
Sequence: F → L |
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
D14056 EMBL· GenBank· DDBJ | BAA03145.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
CP000100 EMBL· GenBank· DDBJ | ABB58144.1 EMBL· GenBank· DDBJ | Genomic DNA |