Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Antitoxin of YafQ-DinJ toxin-antitoxin system; Antitoxin component of a type II toxin-antitoxin (TA) system. A labile antitoxin that counteracts the effect of cognate toxin YafQ. YafQ and DinJ together bind their own promoter, and repress its expression. There are 2 operators with imperfect inverted repeats (IR) in the dinJ promoter, YafQ-(DinJ)2-YafQ only binds to the first (most upstream) of them to repress transcription; binding to a single IR is sufficient for activity in vivo and in vitro. DinJ alone is as potent a transcriptional repressor as the heterotetramer and also only need [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

DNA gyrase (type II topoisomerase), subunit A; A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to maintain chromosomes in an underwound state. This makes better substrates for topoisomerase IV (ParC and ParE) which is the main enzyme that unlinks newly replicated chromosomes in E.coli. Gyrase catalyzes the interconversion of other topological isomers of dsDNA rings, including catenanes. Relaxes negatively supercoiled DNA in an ATP-independent manner. E.coli gyrase has higher supercoiling activity than many other bac [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

mRNA interferase toxin of the HicAB toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. A probable translation-independent mRNA interferase. Overexpression causes cessation of cell growth and inhibits cell proliferation via inhibition of translation; this blockage is overcome (after 90 minutes) by subsequent expression of antitoxin HicB. Overexpression causes cleavage of a number of mRNAs and tmRNA, in a translation-independent fashion, suggesting this is an mRNA interferase. mRNA interferases play a role in bacterial persistence to antibiotics ; Belongs t [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

mRNA interferase toxin of the HigB-HigA toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. A probable translation-dependent mRNA interferase. Overexpression causes cessation of cell growth and inhibits cell proliferation via inhibition of translation; this blockage is overcome by subsequent expression of antitoxin HigA. Overexpression causes cleavage of a number of mRNAs in a translation-dependent fashion, suggesting this is an mRNA interferase. mRNA interferases play a role in bacterial persistence to antibiotics; overexpression of this protein induces p [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Serine/threonine-protein kinase toxin HipA; Toxic component of a type II toxin-antitoxin (TA) system, first identified by mutations that increase production of persister cells, a fraction of cells that are phenotypic variants not killed by antibiotics, which lead to multidrug tolerance. Persistence may be ultimately due to global remodeling of the persister cell's ribosomes. Phosphorylates Glu-tRNA-ligase (AC P04805, gltX, on 'Ser-239') in vivo. Phosphorylation of GltX prevents it from being charged, leading to an increase in uncharged tRNA(Glu). This induces amino acid starvation and [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

DNA-binding ATP-dependent protease La; ATP-dependent serine protease that mediates the selective degradation of mutant and abnormal proteins as well as certain short- lived regulatory proteins, including some antitoxins. Required for cellular homeostasis and for survival from DNA damage and developmental changes induced by stress. Degrades polypeptides processively to yield small peptide fragments that are 5 to 10 amino acids long. Binds to DNA in a double-stranded, site-specific manner. Endogenous substrates include the regulatory proteins RcsA and SulA, the transcriptional activator [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

mRNA interferase toxin, antitoxin is MazE; Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific endoribonuclease it inhibits protein synthesis by cleaving mRNA and inducing bacterial stasis. It is stable, single- strand specific with mRNA cleavage independent of the ribosome, although translation enhances cleavage for some mRNAs. Cleavage occurs at the 5'-end of ACA sequences, yielding a 2',3'-cyclic phosphate and a free 5'-OH, although cleavage can also occur on the 3'-end of the first A. Digests 16S rRNA in vivo 43 nts upstream of the C- terminus; this remove [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

GCU-specific mRNA interferase toxin of the MqsR-MqsA toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. Plays a significant role in the control of biofilm formation and induction of persister cells in the presence of antibiotics. An mRNA interferase which has been reported to be translation-independent. It has also been reported to be translation-dependent. Cleavage has been reported to occur on either side of G in the sequence GCU. Also reported to cleave after C in GC(A/U) sequences. There are only 14 genes in E.coli W3110 (and probably also MG1655) tha [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Antitoxin of the SohA(PrlF)-YhaV toxin-antitoxin system; Antitoxin component of a type II toxin-antitoxin (TA) system. Labile antitoxin that binds to the YhaV toxin and neutralizes its ribonuclease activity. Also acts as a transcription factor. The YhaV/PrlF complex binds the prlF-yhaV operon, probably negatively regulating its expression.

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Antitoxin of the RelE-RelB toxin-antitoxin syste; Antitoxin component of a type II toxin-antitoxin (TA) system. Counteracts the effect of cognate toxin RelE via direct protein-protein interaction, preventing RelE from entering the ribosome A site and thus inhibiting its endoribonuclease activity. An autorepressor of relBE operon transcription. 2 RelB dimers bind to 2 operator sequences; DNA- binding and repression is stronger when complexed with toxin/corepressor RelE by conditional cooperativity. Increased transcription rate of relBE and activation of relE is consistent with a lower l [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Qin prophage; Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific, ribosome-dependent mRNA endoribonuclease that inhibits translation during amino acid starvation (the stringent response). In vitro acts by cleaving mRNA with high codon specificity in the ribosomal A site between positions 2 and 3. The stop codon UAG is cleaved at a fast rate while UAA and UGA are cleaved with intermediate and slow rates. In vitro mRNA cleavage can also occur in the ribosomal E site after peptide release from peptidyl- tRNA in the P site as well as on free 30S subunits. In vivo [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

mRNA interferase toxin of toxin-antitoxin pair YafQ/DinJ; Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific mRNA endoribonuclease that inhibits translation elongation and induces bacterial stasis. Cleavage occurs between the second and third residue of the Lys codon followed by a G or A (5'AAA(G/A)3'), is reading-frame dependent and occurs within the 5' end of most mRNAs. Ribosome-binding confers the sequence specificity and reading frame- dependence. When overexpressed in liquid media YafQ partially inhibits protein synthesis, with a reduction in growth rat [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Antitoxin of the YoeB-YefM toxin-antitoxin system; Antitoxin component of a type II toxin-antitoxin (TA) system. Antitoxin that counteracts the effect of the YoeB toxin. YefM binds to the promoter region of the yefM-yeoB operon to repress transcription, YeoB acts as a corepressor.

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Toxin of the SohB(PrlF)-YhaV toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. Has RNase activity in vitro. Overexpression leads to growth arrest after 30 minutes; these effects are overcome by concomitant expression of antitoxin SohA (PrlF). Massive overexpression is toxic. Unlike most other characterized TA systems degrades rRNA, and co-folding of the both TA proteins is necessary in vitro for inhibition of the RNase activity. It is not known if it has any sequence-specificity. Acts as a transcription factor. The YhaV/PrlF complex binds the prlF-yhaV o [...]

Toxin of the ChpB-ChpS toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. ChpB is a sequence-specific mRNA and (weak) tmRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. Cleavage is independent of the ribosome. Cleavage occurs at ACY sequences where Y is not C. The endoribonuclease activity is not as strong as that of MazF. The endoribonuclease activity (a toxin) is inhibited by its labile cognate antitoxin ChpS. Toxicity results when the levels of ChpS decrease in the cell, leading to mRNA degradation. Both ChpS and ChpB [...]

Toxin of the YoeB-YefM toxin-antitoxin system; Toxic component of a type II toxin-antitoxin (TA) system. Its mode of function is controversial; it has been proposed to be an mRNA interferase but also an inhibitor of translation initiation. When overproduced in wild-type cells, inhibits bacterial growth and translation by cleavage of mRNA molecules while it has a weak effect on colony forming ability. Overproduction of Lon protease specifically activates YoeB-dependent mRNA cleavage, leading to lethality. YefM binds to the promoter region of the yefM-yeoB operon to repress transcription [...]

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

DNA gyrase (type II topoisomerase), subunit A; A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to maintain chromosomes in an underwound state. This makes better substrates for topoisomerase IV (ParC and ParE) which is the main enzyme that unlinks newly replicated chromosomes in E.coli. Gyrase catalyzes the interconversion of other topological isomers of dsDNA rings, including catenanes. Relaxes negatively supercoiled DNA in an ATP-independent manner. E.coli gyrase has higher supercoiling activity than many other bac [...]

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

Peptidase component of the HslUV protease; Protease subunit of a proteasome-like degradation complex believed to be a general protein degrading machinery. The complex has been shown to be involved in the specific degradation of heat shock induced transcription factors such as RpoH and SulA. In addition, small hydrophobic peptides are also hydrolyzed by HslV. HslV has weak protease activity even in the absence of HslU, but this activity is induced more than 100-fold in the presence of HslU. HslU recognizes protein substrates and unfolds these before guiding them to HslV for hydrolysis. [...]

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

DNA-binding ATP-dependent protease La; ATP-dependent serine protease that mediates the selective degradation of mutant and abnormal proteins as well as certain short- lived regulatory proteins, including some antitoxins. Required for cellular homeostasis and for survival from DNA damage and developmental changes induced by stress. Degrades polypeptides processively to yield small peptide fragments that are 5 to 10 amino acids long. Binds to DNA in a double-stranded, site-specific manner. Endogenous substrates include the regulatory proteins RcsA and SulA, the transcriptional activator [...]

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

mRNA interferase toxin, antitoxin is MazE; Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific endoribonuclease it inhibits protein synthesis by cleaving mRNA and inducing bacterial stasis. It is stable, single- strand specific with mRNA cleavage independent of the ribosome, although translation enhances cleavage for some mRNAs. Cleavage occurs at the 5'-end of ACA sequences, yielding a 2',3'-cyclic phosphate and a free 5'-OH, although cleavage can also occur on the 3'-end of the first A. Digests 16S rRNA in vivo 43 nts upstream of the C- terminus; this remove [...]

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

Qin prophage; Toxic component of a type II toxin-antitoxin (TA) system. A sequence-specific, ribosome-dependent mRNA endoribonuclease that inhibits translation during amino acid starvation (the stringent response). In vitro acts by cleaving mRNA with high codon specificity in the ribosomal A site between positions 2 and 3. The stop codon UAG is cleaved at a fast rate while UAA and UGA are cleaved with intermediate and slow rates. In vitro mRNA cleavage can also occur in the ribosomal E site after peptide release from peptidyl- tRNA in the P site as well as on free 30S subunits. In vivo [...]