UniProt functional annotation for P0AA16



	UniProt functional annotation for P0AA16

UniProt code: P0AA16.

Organism: Escherichia coli (strain K12).

Taxonomy: Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales; Enterobacteriaceae; Escherichia.

Function: Member of the two-component regulatory system EnvZ/OmpR involved in osmoregulation (particularly of genes ompF and ompC) as well as other genes (PubMed:3010044, PubMed:3536870). Plays a central role in both acid and osmotic stress responses (PubMed:28526842, PubMed:30524381). Binds to the promoter of both ompC and ompF; at low osmolarity it activates ompF transcription, while at high osmolarity it represses ompF and activates ompC transcription (PubMed:3533941, PubMed:3023382, PubMed:2557454, PubMed:2403550, PubMed:7592927). Involved in acid stress response; this requires EnvZ but not OmpR phosphorylation (PubMed:29138484). Phosphorylated by EnvZ; this stimulates OmpR's DNA-binding ability (PubMed:2656684, PubMed:2668281, PubMed:2668953, PubMed:2674113, PubMed:2558046, PubMed:7934854). Is also dephosphorylated by EnvZ (PubMed:2668281, PubMed:2558046, PubMed:7934854). A single OmpR protein can bind to DNA; OmpR dimers can form on the DNA in either direction, suggesting that interactions between the 2 DNA-binding domains are weak or absent (PubMed:18195018). {ECO:0000269|PubMed:18195018, ECO:0000269|PubMed:2403550, ECO:0000269|PubMed:2557454, ECO:0000269|PubMed:2558046, ECO:0000269|PubMed:2656684, ECO:0000269|PubMed:2668281, ECO:0000269|PubMed:2668953, ECO:0000269|PubMed:2674113, ECO:0000269|PubMed:28526842, ECO:0000269|PubMed:29138484, ECO:0000269|PubMed:3010044, ECO:0000269|PubMed:3023382, ECO:0000269|PubMed:30524381, ECO:0000269|PubMed:3533941, ECO:0000269|PubMed:3536870, ECO:0000269|PubMed:7592927, ECO:0000269|PubMed:7934854}.

Activity regulation: In the presence of 0.2 M NaCl, 2.0 mM sodium cholate (bile salts) decreases expression from the ompC promoter; how this is mediated is unknown. {ECO:0000269|PubMed:28423182}.

Subunit: Monomer in solution. Up to 8 OmpR molecules bind to the ompF promoter; each 20 base pair (bp) region of the promoter binds 2 molecules of OmpR, which may only interact upon DNA-binding. Binds to direct repeats in the 20 bp DNA fragments (PubMed:7592927). At pH 7.1 protein is monomeric, as the pH decreases to 6.5 and 6.1 about 70% is dimeric, which is poorly phosphorylated. DNA-binding ability increases at acidic pH (PubMed:29138484). {ECO:0000269|PubMed:29138484, ECO:0000269|PubMed:7592927}.

Subcellular location: Cytoplasm {ECO:0000269|PubMed:3533941}.

Induction: 1.8-fold induced by growth in 15% sucrose, no change upon growth at pH 5.6 (PubMed:30524381). Part of the ompR-envZ operon (Probable). {ECO:0000269|PubMed:30524381, ECO:0000305|PubMed:2997120, ECO:0000305|PubMed:6292199}.

Domain: Composed of an N-terminal response regulatory domain joined by a flexible linker to the C-terminal DNA-binding domain; the relative conformation of the 2 domains alters upon phosphorylation. {ECO:0000269|PubMed:7568033}.

Ptm: Phosphorylated by EnvZ (PubMed:2656684, PubMed:2668281, PubMed:2674113, PubMed:7934854, PubMed:2277041). Asp-55 is the primary phosphate acceptor site, but Asp-11 may also serve as a phosphorylation site, particularly in the absence of Asp-55 (PubMed:7934854) (Probable). Phosphorylation stimulates the DNA-binding ability of OmpR (PubMed:2674113). Dephosphorylated by EnvZ in the presence of ATP (PubMed:2668281, PubMed:2558046, PubMed:7934854). {ECO:0000269|PubMed:2277041, ECO:0000269|PubMed:2558046, ECO:0000269|PubMed:2656684, ECO:0000269|PubMed:2668281, ECO:0000269|PubMed:2674113, ECO:0000269|PubMed:7934854, ECO:0000305|PubMed:2277041}.

Mass spectrometry: Mass=27355; Method=Electrospray; Evidence={ECO:0000269|PubMed:7568033};

Mass spectrometry: Mass=27438; Method=Electrospray; Note=The (mono)phosphorylated form.; Evidence={ECO:0000269|PubMed:7568033};

Disruption phenotype: Loss of expression of OmpC and OmpF under low and high osmolarity (PubMed:7934854). Deletion of both ompR and envZ leads to loss of both OmpC and OmpF expression under 0% and 15% sucrose (PubMed:2277041). Cells no longer reduce their internal pH in response to external acid stress (PubMed:29138484). {ECO:0000269|PubMed:2277041, ECO:0000269|PubMed:29138484, ECO:0000269|PubMed:7934854}.

Miscellaneous: Cross talk between this and the Che and Ntr two- component systems can occur at least in vitro. {ECO:0000269|PubMed:2558046}.

Sequence caution: Sequence=Ref.1; Type=Frameshift; Evidence={ECO:0000269|PubMed:2997120, ECO:0000269|PubMed:3010044};

Annotations taken from UniProtKB at the EBI.


Organism:		Escherichia coli (strain K12).
Taxonomy:		Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales; Enterobacteriaceae; Escherichia.



Function:		Member of the two-component regulatory system EnvZ/OmpR involved in osmoregulation (particularly of genes ompF and ompC) as well as other genes (PubMed:3010044, PubMed:3536870). Plays a central role in both acid and osmotic stress responses (PubMed:28526842, PubMed:30524381). Binds to the promoter of both ompC and ompF; at low osmolarity it activates ompF transcription, while at high osmolarity it represses ompF and activates ompC transcription (PubMed:3533941, PubMed:3023382, PubMed:2557454, PubMed:2403550, PubMed:7592927). Involved in acid stress response; this requires EnvZ but not OmpR phosphorylation (PubMed:29138484). Phosphorylated by EnvZ; this stimulates OmpR's DNA-binding ability (PubMed:2656684, PubMed:2668281, PubMed:2668953, PubMed:2674113, PubMed:2558046, PubMed:7934854). Is also dephosphorylated by EnvZ (PubMed:2668281, PubMed:2558046, PubMed:7934854). A single OmpR protein can bind to DNA; OmpR dimers can form on the DNA in either direction, suggesting that interactions between the 2 DNA-binding domains are weak or absent (PubMed:18195018). {ECO:0000269\|PubMed:18195018, ECO:0000269\|PubMed:2403550, ECO:0000269\|PubMed:2557454, ECO:0000269\|PubMed:2558046, ECO:0000269\|PubMed:2656684, ECO:0000269\|PubMed:2668281, ECO:0000269\|PubMed:2668953, ECO:0000269\|PubMed:2674113, ECO:0000269\|PubMed:28526842, ECO:0000269\|PubMed:29138484, ECO:0000269\|PubMed:3010044, ECO:0000269\|PubMed:3023382, ECO:0000269\|PubMed:30524381, ECO:0000269\|PubMed:3533941, ECO:0000269\|PubMed:3536870, ECO:0000269\|PubMed:7592927, ECO:0000269\|PubMed:7934854}.


Activity regulation:		In the presence of 0.2 M NaCl, 2.0 mM sodium cholate (bile salts) decreases expression from the ompC promoter; how this is mediated is unknown. {ECO:0000269\|PubMed:28423182}.
Subunit:		Monomer in solution. Up to 8 OmpR molecules bind to the ompF promoter; each 20 base pair (bp) region of the promoter binds 2 molecules of OmpR, which may only interact upon DNA-binding. Binds to direct repeats in the 20 bp DNA fragments (PubMed:7592927). At pH 7.1 protein is monomeric, as the pH decreases to 6.5 and 6.1 about 70% is dimeric, which is poorly phosphorylated. DNA-binding ability increases at acidic pH (PubMed:29138484). {ECO:0000269\|PubMed:29138484, ECO:0000269\|PubMed:7592927}.
Subcellular location:		Cytoplasm {ECO:0000269\|PubMed:3533941}.
Induction:		1.8-fold induced by growth in 15% sucrose, no change upon growth at pH 5.6 (PubMed:30524381). Part of the ompR-envZ operon (Probable). {ECO:0000269\|PubMed:30524381, ECO:0000305\|PubMed:2997120, ECO:0000305\|PubMed:6292199}.
Domain:		Composed of an N-terminal response regulatory domain joined by a flexible linker to the C-terminal DNA-binding domain; the relative conformation of the 2 domains alters upon phosphorylation. {ECO:0000269\|PubMed:7568033}.
Ptm:		Phosphorylated by EnvZ (PubMed:2656684, PubMed:2668281, PubMed:2674113, PubMed:7934854, PubMed:2277041). Asp-55 is the primary phosphate acceptor site, but Asp-11 may also serve as a phosphorylation site, particularly in the absence of Asp-55 (PubMed:7934854) (Probable). Phosphorylation stimulates the DNA-binding ability of OmpR (PubMed:2674113). Dephosphorylated by EnvZ in the presence of ATP (PubMed:2668281, PubMed:2558046, PubMed:7934854). {ECO:0000269\|PubMed:2277041, ECO:0000269\|PubMed:2558046, ECO:0000269\|PubMed:2656684, ECO:0000269\|PubMed:2668281, ECO:0000269\|PubMed:2674113, ECO:0000269\|PubMed:7934854, ECO:0000305\|PubMed:2277041}.
Mass spectrometry:		Mass=27355; Method=Electrospray; Evidence={ECO:0000269\|PubMed:7568033};
Mass spectrometry:		Mass=27438; Method=Electrospray; Note=The (mono)phosphorylated form.; Evidence={ECO:0000269\|PubMed:7568033};
Disruption phenotype:		Loss of expression of OmpC and OmpF under low and high osmolarity (PubMed:7934854). Deletion of both ompR and envZ leads to loss of both OmpC and OmpF expression under 0% and 15% sucrose (PubMed:2277041). Cells no longer reduce their internal pH in response to external acid stress (PubMed:29138484). {ECO:0000269\|PubMed:2277041, ECO:0000269\|PubMed:29138484, ECO:0000269\|PubMed:7934854}.
Miscellaneous:		Cross talk between this and the Che and Ntr two- component systems can occur at least in vitro. {ECO:0000269\|PubMed:2558046}.
Sequence caution:		Sequence=Ref.1; Type=Frameshift; Evidence={ECO:0000269\|PubMed:2997120, ECO:0000269\|PubMed:3010044};