1ub4: Difference between revisions
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ub4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ub4 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1ub4 RCSB], [http://www.ebi.ac.uk/pdbsum/1ub4 PDBsum], [http://www.topsan.org/Proteins/NYSGXRC/1ub4 TOPSAN]</span></td></tr> | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ub4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ub4 OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1ub4 RCSB], [http://www.ebi.ac.uk/pdbsum/1ub4 PDBsum], [http://www.topsan.org/Proteins/NYSGXRC/1ub4 TOPSAN]</span></td></tr> | ||
</table> | </table> | ||
== Function == | |||
[[http://www.uniprot.org/uniprot/CHPA_ECOLI CHPA_ECOLI]] Toxic component of a toxin-antitoxin (TA) module. MazF is a sequence-specific mRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. It is very stable, single-strand specific and cleavage is independent of the ribosome, although translation enhances cleavage for some mRNAs. Cleavage usually occurs between the first A and C of ACA sequences, yielding a 2',3'-cyclic phosphate and a free 5'-OH. The endoribonuclease activity (a toxin) is inhibited by the labile cognate antitoxin MazE. Toxicity results when the levels of MazE decrease in the cell, leading to mRNA degradation. This effect can be rescued by expression of MazE, but after 6 hours in rich medium overexpression of MazF leads to programmed cell death. MazF-mediated cell death occurs following a number of stress conditions in a relA-dependent fashion and only when cells are in log phase. Cell growth and viability are not affected when MazF and MazE are coexpressed. Programmed cell death occurs when cells are at high density and depends on the presence of MazEF and a quorum sensing pentapeptide, the extracellular death factor (EDF) with sequence NNWNN, probably produced from the zwg gene product glucose-6-phosphate 1-dehydrogenase. Both MazE and MazEF bind to the promoter region of the mazEF operon to inhibit their transcription.<ref>PMID:8650219</ref> <ref>PMID:12123459</ref> <ref>PMID:15150257</ref> <ref>PMID:15576778</ref> <ref>PMID:15316771</ref> <ref>PMID:15537630</ref> <ref>PMID:19707553</ref> Might also serve to protect cells against bacteriophage; in the presence of MazEF fewer P1 phage are produced than in a disruption strain. For strain K38 most wild-type cells are killed by not by phage lysis; it was suggested that MazEF causes P1 phage exclusion from the bacterial population. This phenomenon is strain dependent.<ref>PMID:8650219</ref> <ref>PMID:12123459</ref> <ref>PMID:15150257</ref> <ref>PMID:15576778</ref> <ref>PMID:15316771</ref> <ref>PMID:15537630</ref> <ref>PMID:19707553</ref> Cell death governed by the mazEF and dinJ-yafQ TA modules seems to play a role in biofilm formation, while mazEF is also implicated in cell death in liquid media.<ref>PMID:8650219</ref> <ref>PMID:12123459</ref> <ref>PMID:15150257</ref> <ref>PMID:15576778</ref> <ref>PMID:15316771</ref> <ref>PMID:15537630</ref> <ref>PMID:19707553</ref> [[http://www.uniprot.org/uniprot/CHPR_ECOLI CHPR_ECOLI]] Antitoxin component of a toxin-antitoxin (TA) module. Labile antitoxin that binds to the MazF mRNA interferase toxin and neutralizes its endoribonuclease activity. Is considered to be an 'addiction' molecule as the cell will die in its absence. The endoribonuclease activity (MazF, a toxin) is inhibited by the labile cognate antitoxin MazE. Toxicity results when the levels of MazE decrease in the cell, leading to mRNA degradation. This effect can be rescued by expression of MazE, but after 6 hours in rich medium the overexpression of MazF leads to programmed cell death. Cell growth and viability are not affected when MazF and MazE are coexpressed. Both MazE and MazE-MazF bind to the promoter region of the mazE-mazF operon to inhibit their transcription.<ref>PMID:8650219</ref> <ref>PMID:12123459</ref> <ref>PMID:15576778</ref> <ref>PMID:19707553</ref> Cell death governed by the MazE-MazF and DinJ-YafQ TA modules seems to play a role in biofilm formation, while MazE-MazF is also implicated in cell death in liquid media.<ref>PMID:8650219</ref> <ref>PMID:12123459</ref> <ref>PMID:15576778</ref> <ref>PMID:19707553</ref> | |||
== Evolutionary Conservation == | == Evolutionary Conservation == | ||
[[Image:Consurf_key_small.gif|200px|right]] | [[Image:Consurf_key_small.gif|200px|right]] |
Revision as of 14:49, 25 December 2014
crystal structure of MazEF complexcrystal structure of MazEF complex
Structural highlights
Function[CHPA_ECOLI] Toxic component of a toxin-antitoxin (TA) module. MazF is a sequence-specific mRNA endoribonuclease that inhibits protein synthesis and induces bacterial stasis. It is very stable, single-strand specific and cleavage is independent of the ribosome, although translation enhances cleavage for some mRNAs. Cleavage usually occurs between the first A and C of ACA sequences, yielding a 2',3'-cyclic phosphate and a free 5'-OH. The endoribonuclease activity (a toxin) is inhibited by the labile cognate antitoxin MazE. Toxicity results when the levels of MazE decrease in the cell, leading to mRNA degradation. This effect can be rescued by expression of MazE, but after 6 hours in rich medium overexpression of MazF leads to programmed cell death. MazF-mediated cell death occurs following a number of stress conditions in a relA-dependent fashion and only when cells are in log phase. Cell growth and viability are not affected when MazF and MazE are coexpressed. Programmed cell death occurs when cells are at high density and depends on the presence of MazEF and a quorum sensing pentapeptide, the extracellular death factor (EDF) with sequence NNWNN, probably produced from the zwg gene product glucose-6-phosphate 1-dehydrogenase. Both MazE and MazEF bind to the promoter region of the mazEF operon to inhibit their transcription.[1] [2] [3] [4] [5] [6] [7] Might also serve to protect cells against bacteriophage; in the presence of MazEF fewer P1 phage are produced than in a disruption strain. For strain K38 most wild-type cells are killed by not by phage lysis; it was suggested that MazEF causes P1 phage exclusion from the bacterial population. This phenomenon is strain dependent.[8] [9] [10] [11] [12] [13] [14] Cell death governed by the mazEF and dinJ-yafQ TA modules seems to play a role in biofilm formation, while mazEF is also implicated in cell death in liquid media.[15] [16] [17] [18] [19] [20] [21] [CHPR_ECOLI] Antitoxin component of a toxin-antitoxin (TA) module. Labile antitoxin that binds to the MazF mRNA interferase toxin and neutralizes its endoribonuclease activity. Is considered to be an 'addiction' molecule as the cell will die in its absence. The endoribonuclease activity (MazF, a toxin) is inhibited by the labile cognate antitoxin MazE. Toxicity results when the levels of MazE decrease in the cell, leading to mRNA degradation. This effect can be rescued by expression of MazE, but after 6 hours in rich medium the overexpression of MazF leads to programmed cell death. Cell growth and viability are not affected when MazF and MazE are coexpressed. Both MazE and MazE-MazF bind to the promoter region of the mazE-mazF operon to inhibit their transcription.[22] [23] [24] [25] Cell death governed by the MazE-MazF and DinJ-YafQ TA modules seems to play a role in biofilm formation, while MazE-MazF is also implicated in cell death in liquid media.[26] [27] [28] [29] Evolutionary Conservation![]() Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA structure of the Escherichia coli chromosomal MazE/MazF addiction module has been determined at 1.7 A resolution. Addiction modules consist of stable toxin and unstable antidote proteins that govern bacterial cell death. MazE (antidote) and MazF (toxin) form a linear heterohexamer composed of alternating toxin and antidote homodimers (MazF(2)-MazE(2)-MazF(2)). The MazE homodimer contains a beta barrel from which two extended C termini project, making interactions with flanking MazF homodimers that resemble the plasmid-encoded toxins CcdB and Kid. The MazE/MazF heterohexamer structure documents that the mechanism of antidote-toxin recognition is common to both chromosomal and plasmid-borne addiction modules, and provides general molecular insights into toxin function, antidote degradation in the absence of toxin, and promoter DNA binding by antidote/toxin complexes. Crystal structure of the MazE/MazF complex: molecular bases of antidote-toxin recognition.,Kamada K, Hanaoka F, Burley SK Mol Cell. 2003 Apr;11(4):875-84. PMID:12718874[30] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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