UniProt functional annotation for P23873



	UniProt functional annotation for P23873

UniProt code: P23873.

Organism: Escherichia coli (strain K12).

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

Function: Antitoxin component of a type II toxin-antitoxin (TA) system. Neutralizes the toxic effect of cognate toxin HipA (PubMed:20616060). Also neutralizes the toxic effect of non-cognate toxin YjjJ (PubMed:28430938). Binds to operator sites with the consensus sequence 5-'TATCCN(8)GGATA-3' to repress the hipBA operon promoter (PubMed:8021189, PubMed:19150849); binding of HipB(2) to DNA induces a 70 degree bend (PubMed:19150849). This forces HipA dimerization, which blocks HipA's active site and thus its toxic action (PubMed:26222023). May play a role in biofilm formation (PubMed:23329678). {ECO:0000269|PubMed:19150849, ECO:0000269|PubMed:20616060, ECO:0000269|PubMed:23329678, ECO:0000269|PubMed:26222023, ECO:0000269|PubMed:28430938, ECO:0000269|PubMed:8021189}.

Activity regulation: Degraded by Lon protease; degradation is inhibited in a HipA-HipB complex and when bound to the operator consensus sequence dsDNA. {ECO:0000269|PubMed:22720069}.

Subunit: Homodimer (PubMed:8021189). Binds operator DNA sites in the absence of HipA, inducing a 70 degree bend in consecutive operators and deforming DNA between the operators so that HipB dimers bind on opposite faces of the DNA (PubMed:26222023). Forms a HipA(2)HipB(2) heterotetramer which can interact with a single operator site on DNA, inducing a 70 degree bend (PubMed:19150849). When 2 operators are present each HipB dimer contacts 1 HipA molecule, which are brought together by the DNA bend and dimerize, blocking the HipA active site and inactivating its toxic activity (PubMed:26222023). HipA-HipB- induced bending also distorts the -35 and -10 boxes of the promoter and probably prevents sigma-factor binding, and additionally bound HipB and HipA block RNA polymerase access to the -35 box, thus repressing the operon (PubMed:26222023). This complex also blocks the toxic activity of HipA (PubMed:19150849). Mutations present in allele hipA7 (G22S and D291A) decrease the affinity of HipA for HipB (PubMed:20616060). {ECO:0000269|PubMed:19150849, ECO:0000269|PubMed:19622872, ECO:0000269|PubMed:20616060, ECO:0000269|PubMed:24089363, ECO:0000269|PubMed:26222023, ECO:0000269|PubMed:8021189}.

Ptm: Degraded by Lon protease in vivo; half-life is 17 minutes in wild- type cells and over 200 minutes in a lon deletion strain. In vitro degradation by Lon is Mg(2+)-ATP-dependent (PubMed:22720069). {ECO:0000269|PubMed:22720069}.

Disruption phenotype: Cannot be disrupted, suggesting it is a functional antitoxin; no visible phenotype when the hipBA operon is deleted (PubMed:8021189, PubMed:20616060). A hipA or a hipB-hipA operon deletion show decreased biofilm production in the absence of antibiotics (PubMed:23329678). {ECO:0000269|PubMed:20616060, ECO:0000269|PubMed:23329678, ECO:0000269|PubMed:8021189}.

Annotations taken from UniProtKB at the EBI.


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



Function:		Antitoxin component of a type II toxin-antitoxin (TA) system. Neutralizes the toxic effect of cognate toxin HipA (PubMed:20616060). Also neutralizes the toxic effect of non-cognate toxin YjjJ (PubMed:28430938). Binds to operator sites with the consensus sequence 5-'TATCCN(8)GGATA-3' to repress the hipBA operon promoter (PubMed:8021189, PubMed:19150849); binding of HipB(2) to DNA induces a 70 degree bend (PubMed:19150849). This forces HipA dimerization, which blocks HipA's active site and thus its toxic action (PubMed:26222023). May play a role in biofilm formation (PubMed:23329678). {ECO:0000269\|PubMed:19150849, ECO:0000269\|PubMed:20616060, ECO:0000269\|PubMed:23329678, ECO:0000269\|PubMed:26222023, ECO:0000269\|PubMed:28430938, ECO:0000269\|PubMed:8021189}.


Activity regulation:		Degraded by Lon protease; degradation is inhibited in a HipA-HipB complex and when bound to the operator consensus sequence dsDNA. {ECO:0000269\|PubMed:22720069}.
Subunit:		Homodimer (PubMed:8021189). Binds operator DNA sites in the absence of HipA, inducing a 70 degree bend in consecutive operators and deforming DNA between the operators so that HipB dimers bind on opposite faces of the DNA (PubMed:26222023). Forms a HipA(2)HipB(2) heterotetramer which can interact with a single operator site on DNA, inducing a 70 degree bend (PubMed:19150849). When 2 operators are present each HipB dimer contacts 1 HipA molecule, which are brought together by the DNA bend and dimerize, blocking the HipA active site and inactivating its toxic activity (PubMed:26222023). HipA-HipB- induced bending also distorts the -35 and -10 boxes of the promoter and probably prevents sigma-factor binding, and additionally bound HipB and HipA block RNA polymerase access to the -35 box, thus repressing the operon (PubMed:26222023). This complex also blocks the toxic activity of HipA (PubMed:19150849). Mutations present in allele hipA7 (G22S and D291A) decrease the affinity of HipA for HipB (PubMed:20616060). {ECO:0000269\|PubMed:19150849, ECO:0000269\|PubMed:19622872, ECO:0000269\|PubMed:20616060, ECO:0000269\|PubMed:24089363, ECO:0000269\|PubMed:26222023, ECO:0000269\|PubMed:8021189}.
Ptm:		Degraded by Lon protease in vivo; half-life is 17 minutes in wild- type cells and over 200 minutes in a lon deletion strain. In vitro degradation by Lon is Mg(2+)-ATP-dependent (PubMed:22720069). {ECO:0000269\|PubMed:22720069}.
Disruption phenotype:		Cannot be disrupted, suggesting it is a functional antitoxin; no visible phenotype when the hipBA operon is deleted (PubMed:8021189, PubMed:20616060). A hipA or a hipB-hipA operon deletion show decreased biofilm production in the absence of antibiotics (PubMed:23329678). {ECO:0000269\|PubMed:20616060, ECO:0000269\|PubMed:23329678, ECO:0000269\|PubMed:8021189}.