| IED ID | IndEnz0002002598 |
| Enzyme Type ID | protease002598 |
| Protein Name |
Endoribonuclease toxin MazF EC 3.1.27.- Toxin MazF mRNA interferase MazF |
| Gene Name | mazF chpA chpAK b2782 JW2753 |
| Organism | Escherichia coli (strain K12) |
| Taxonomic Lineage | cellular organisms Bacteria Proteobacteria Gammaproteobacteria Enterobacterales Enterobacteriaceae Escherichia Escherichia coli Escherichia coli (strain K12) |
| Enzyme Sequence | MVSRYVPDMGDLIWVDFDPTKGSEQAGHRPAVVLSPFMYNNKTGMCLCVPCTTQSKGYPFEVVLSGQERDGVALADQVKSIAWRARGATKKGTVAPEELQLIKAKINVLIG |
| Enzyme Length | 111 |
| Uniprot Accession Number | P0AE70 |
| Absorption | |
| Active Site | |
| Activity Regulation | ACTIVITY REGULATION: (Microbial infection) RNA cleavage activity is reduced when ADP-ribosylated. {ECO:0000269|PubMed:26395283}.; ACTIVITY REGULATION: Inhibited by Mg(2+) (PubMed:15537630). Stimulated in vitro in a concentration-dependent fashion by EDF, which is able to overcome inhibition by cognate antitoxin MazE (PubMed:21419338). The TA system is antagonized by stress response kinase SrkA, but probably not by phosphorylation of MazF (PubMed:23416055). {ECO:0000269|PubMed:15537630, ECO:0000269|PubMed:21419338, ECO:0000269|PubMed:23416055}. |
| Binding Site | |
| Calcium Binding | |
| catalytic Activity | |
| DNA Binding | |
| EC Number | 3.1.27.- |
| Enzyme Function | FUNCTION: 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 (PubMed:18854355). 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 (PubMed:15537630, PubMed:23280569). Digests 16S rRNA in vivo 43 nts upstream of the C-terminus; this removes the anti-Shine-Dalgarno sequence forming a mixed population of wild-type and 'stress ribosomes'. Stress ribosomes do not translate leader-containing mRNA but are proficient in translation of leaderless mRNA, which alters the protein expression profile of the cell; MazF produces some leaderless mRNA (PubMed:21944167). The toxic endoribonuclease activity is inhibited by its 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 (PubMed:8650219, PubMed:11222603). MazF-mediated cell death occurs following a number of stress conditions in a relA-dependent fashion and only when cells are in log phase; sigma factor S (rpoS) protects stationary phase cells from MazF-killing (PubMed:15150257, PubMed:19251848). 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 own transcription. MazE has higher affinity for promoter DNA in the presence of MazF (PubMed:25564525). Cross-talk can occur between different TA systems, ectopic expression of this toxin induces transcription of the relBEF TA system operon with specific cleavage of the mRNA produced (PubMed:23432955). {ECO:0000269|PubMed:11071896, ECO:0000269|PubMed:11222603, ECO:0000269|PubMed:15150257, ECO:0000269|PubMed:15537630, ECO:0000269|PubMed:18854355, ECO:0000269|PubMed:19251848, ECO:0000269|PubMed:21944167, ECO:0000269|PubMed:23280569, ECO:0000269|PubMed:23432955, ECO:0000269|PubMed:25564525, ECO:0000269|PubMed:8650219}.; FUNCTION: Might also serve to protect cells against bacteriophage; in the presence of MazE-MazF fewer P1 phages are produced than in a disrupted strain. For strain K38 most wild-type cells are killed but not by phage lysis; it was suggested that MazE-MazF causes P1 phage exclusion from the bacterial population. This phenomenon is strain dependent. {ECO:0000269|PubMed:15316771}.; FUNCTION: The physiological role of this TA system is debated. Programmed cell death (PCD) occurs when cells are at high density and depends on the presence of MazE-MazF and a quorum sensing pentapeptide, the extracellular death factor (EDF) with sequence Asn-Asn-Trp-Asn-Asn (NNWNN), probably produced from the zwf gene product glucose-6-phosphate 1-dehydrogenase (PubMed:17962566, PubMed:18310334). Cell death governed by the MazE-MazF and DinJ-YafQ TA systems seems to play a role in biofilm formation, while MazE-MazF is also implicated in cell death in liquid media (PubMed:19707553). Implicated in hydroxy radical-mediated cell death induced by hydroxyurea treatment (PubMed:20005847, PubMed:23416055). In conjunction with EDF prevents apoptotic-like death (ALD) in the presence of DNA damaging agents, probably by reducing recA mRNA levels in a non-endonuclease-mediated manner (PubMed:22412352). Other studies (in strains BW25113 and MC4100, the latter makes EDF) demonstrate MazF does not cause PCD but instead bacteriostasis and possibly a dormant state as well as persister cell generation (PubMed:24375411). {ECO:0000269|PubMed:17962566, ECO:0000269|PubMed:18310334, ECO:0000269|PubMed:19707553, ECO:0000269|PubMed:20005847, ECO:0000269|PubMed:21419338, ECO:0000269|PubMed:22412352, ECO:0000269|PubMed:23416055, ECO:0000269|PubMed:24375411, ECO:0000269|PubMed:8650219}. |
| Temperature Dependency | |
| PH Dependency | |
| Pathway | |
| nucleotide Binding | |
| Features | Beta strand (8); Chain (1); Helix (4); Modified residue (1); Mutagenesis (8); Region (2); Turn (1) |
| Keywords | 3D-structure;ADP-ribosylation;Antiviral defense;DNA-binding;Endonuclease;Hydrolase;Nuclease;Quorum sensing;RNA-binding;Reference proteome;Repressor;Stress response;Toxin-antitoxin system;Transcription;Transcription regulation;Translation regulation |
| Interact With | |
| Induction | INDUCTION: Expressed in exponentially growing cells. Induction has been reported to occur after amino acid starvation in a ppGpp-independent fashion and to be Lon protease-dependent (PubMed:12972253), but also to not occur after amino acid starvation and to be regulated by ppGpp (PubMed:8650219). Also induced in M9 minimal medium and by chloramphenicol treatment (PubMed:21944167). MazE alone and in combination with MazF, represses transcription of the mazE-mazF operon. Fis activates transcription. Part of the relA-mazE-mazF-mazG operon, there is also a second mazE-mazF specific promoter which is negatively autoregulated (PubMed:2844820, PubMed:8650219). Operon induced by ectopic expression of toxin RelE; operon induction by amino acid starvation requires the relBEF operon (PubMed:23432955). {ECO:0000269|PubMed:11071896, ECO:0000269|PubMed:12972253, ECO:0000269|PubMed:16390452, ECO:0000269|PubMed:21944167, ECO:0000269|PubMed:23432955, ECO:0000269|PubMed:2844820, ECO:0000269|PubMed:8650219}. |
| Subcellular Location | |
| Modified Residue | MOD_RES 4; /note=ADP-ribosylarginine; /evidence=ECO:0000269|PubMed:26395283 |
| Post Translational Modification | PTM: (Microbial infection) ADP-ribosylated by enterobacteria phage T4. {ECO:0000269|PubMed:26395283}. |
| Signal Peptide | |
| Structure 3D | X-ray crystallography (12) |
| Cross Reference PDB | 1UB4; 3NFC; 5CK9; 5CKB; 5CKD; 5CKE; 5CKF; 5CKH; 5CO7; 5CQX; 5CQY; 5CR2; |
| Mapped Pubmed ID | 16606699; 27026704; |
| Motif | |
| Gene Encoded By | |
| Mass | 12,098 |
| Kinetics | |
| Metal Binding | |
| Rhea ID | |
| Cross Reference Brenda |