mazF

Functionⁱ

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).11 Publications

Might also serve to protect cells against bacteriophage; in the presence of MazE-MazF fewer P1 phage 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.1 Publication

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). mRNA interferases play a role in bacterial persistence to antibiotics; overexpression of this protein induces persisters resistant to ciprofloxacin and ampicillin (PubMed:21788497).10 Publications

Caution

Strain K12 / MG1655 is deficient in both production and response to EDF, unlike strains K12 / MC4100, K12 / W3110 and K12 / K38, all of which make and respond to EDF.1 Publication

Activity regulationⁱ

Inhibited by Mg²⁺ (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).3 Publications

GO - Molecular functionⁱ

DNA binding Source: UniProtKB-KW
endoribonuclease activity
Source: UniProtKB
Inferred from direct assayⁱ
- 12972253
protein-containing complex binding
Source: CAFA
Inferred from direct assayⁱ
- 12718874
protein homodimerization activity
Source: CAFA
Inferred from direct assayⁱ
- 12718874
RNA binding Source: UniProtKB-KW

View the complete GO annotation on QuickGO ...

GO - Biological processⁱ

defense response to virus Source: UniProtKB-KW
mRNA catabolic process
Source: UniProtKB
Inferred from direct assayⁱ
- 12972253
negative regulation of cell growth
Source: UniProtKB
Inferred from mutant phenotypeⁱ
- 8650219
protein heterooligomerization
Source: CAFA
Inferred from direct assayⁱ
- 12718874
quorum sensing Source: UniProtKB-KW
regulation of transcription, DNA-templated Source: UniProtKB-KW
regulation of translation Source: UniProtKB-KW
rRNA catabolic process
Source: UniProtKB
Inferred from direct assayⁱ
- 21944167
transcription, DNA-templated Source: UniProtKB-KW

View the complete GO annotation on QuickGO ...

Keywordsⁱ

Molecular function	DNA-binding, Endonuclease, Hydrolase, Nuclease, Repressor, RNA-binding
Biological process	Antiviral defense, Quorum sensing, Stress response, Toxin-antitoxin system, Transcription, Transcription regulation, Translation regulation

Enzyme and pathway databases

BioCycⁱ	EcoCyc:EG11249-MONOMER MetaCyc:EG11249-MONOMER

BioCycⁱ

EcoCyc:EG11249-MONOMER
MetaCyc:EG11249-MONOMER

Names & Taxonomyⁱ

Protein namesⁱ	Recommended name: Endoribonuclease toxin MazF (EC:3.1.27.-1 Publication) Alternative name(s): Toxin MazF mRNA interferase MazF1 Publication
Gene namesⁱ	Name:mazF Synonyms:chpA, chpAK Ordered Locus Names:b2782, JW2753
Organismⁱ	Escherichia coli (strain K12)
Taxonomic identifierⁱ	83333 [NCBI]
Taxonomic lineageⁱ	cellular organisms › Bacteria › Proteobacteria › Gammaproteobacteria › Enterobacterales › Enterobacteriaceae › Escherichia › Escherichia coli
Proteomesⁱ	UP000000318 Componentⁱ: Chromosome UP000000625 Componentⁱ: Chromosome

Organism-specific databases

EcoGeneⁱ	EG11249 mazF

EcoGeneⁱ

EG11249 mazF

Subcellular locationⁱ

GO - Cellular componentⁱ

protein-containing complex
Source: CAFA
Inferred from direct assayⁱ
- 12718874

View the complete GO annotation on QuickGO ...

Pathology & Biotechⁱ

Biotechnological useⁱ

Can be used to produce large quantities of a single protein if the gene coding for the protein does not contain any ACA codons. Up to 90% of expressed bacterial cellular protein can be the target, which can be produced for up to 4 days. The system also works in eukaryotic cells.1 Publication

Disruption phenotypeⁱ

Decreased sensitivity to dramatic intracellular increases of ppGpp. Cells missing mazE-mazF survive high temperature, various DNA-damaging agents and H₂O₂ exposure better than wild-type cells. Cells missing mazE-mazF produce more P1 phage than wild-type cells, while introduction of lysogens into a growing non-lysogenic disruption culture is lethal (PubMed:15316771). Cells missing mazE-mazF show reduced biofilm formation, and survive antibiotic treatment in log phase better than wild-type cells (PubMed:11222603, PubMed:19707553). However lag phase cells disrupted only for mazF had a lower survival rate than wild-type cells (PubMed:24375411). Cells missing mazE-mazF survive hydroxyurea treatment better than wild-type; further disruption of relE-relB and tonB yields even better survival (PubMed:20005847). Cells missing mazE-mazF undergo an apoptotic-like death (ALD) upon DNA damage characterized by membrane depolarization and DNA fragmentation; further disruption of recA prevents membrane depolarization (PubMed:22412352). Unlike the single srkA disruption mutant, a triple srkA-mazE-mazF disruption mutant shows no hyperlethality in the presence of nalidixic acid or UV light, suggesting SrkA has a negative effect on MazF (PubMed:23416055). mRNA interferases play a role in bacterial persistence to antibiotics; as 10 mRNA interferases are successively deleted reduced levels of persisters are generated (PubMed:21788497).11 Publications

Mutagenesis

Feature key	Position(s)	DescriptionActions	Length
Mutagenesisⁱ	17 – 28	FDPTK…EQAGH → GGGGGGGGGGG: Changes loop 1 to poly-G; loss of endoribonuclease activity. 1 PublicationAdd BLAST	12
Mutagenesisⁱ	17 – 28	FDPTK…EQAGH → LGPPSGSQPAKR: Changes loop 1 to MazF6 M.tuberculosis sequence; loss of endoribonuclease activity. 1 PublicationAdd BLAST	12
Mutagenesisⁱ	17 – 28	FDPTK…EQAGH → PDDSRGPVPSYS: Changes loop 1 to MazF M.xanthus sequence; loss of endoribonuclease activity. 1 PublicationAdd BLAST	12
Mutagenesisⁱ	24	E → A: Greatly reduces toxicity, about 10-fold less RNA cleavage activity. Expression in the presence of wt MazF has a dominant-negative phenotype, causing cell death as it titrates out the MazE antitoxin; still activates operon transcription. 2 Publications	1
Mutagenesisⁱ	28	H → A: No changes in toxicity. 1 Publication	1
Mutagenesisⁱ	53 – 61	TQSKGYPFE → GGGGGGGG or GGGGGGGGGGG: Changes loop 2 to poly-G; reduces endoribonuclease activity, alters cleavage sites. 1 Publication	9
Mutagenesisⁱ	53 – 61	TQSKGYPFE → SNLHRASEPGN: Changes loop 2 to MazF M.xanthus sequence; reduces endoribonuclease activity, alters cleavage sites. 1 Publication	9
Mutagenesisⁱ	53 – 61	TQSKGYPFE → SNTALAAMPGN: Changes loop 2 to MazF6 M.tuberculosis sequence; reduces endoribonuclease activity, alters cleavage sites. 1 Publication	9

Chemistry databases

ChEMBLⁱ	CHEMBL1795096

ChEMBLⁱ

CHEMBL1795096

PTM / Processingⁱ

Molecule processing

Feature key	Position(s)	DescriptionActions	Graphical view	Length
ChainⁱPRO_0000201897	1 – 111	Endoribonuclease toxin MazFAdd BLAST		111

Proteomic databases

PaxDbⁱ	P0AE70
PRIDEⁱ	P0AE70

Expressionⁱ

Inductionⁱ

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).7 Publications

Interactionⁱ

Subunit structureⁱ

Probably a dimer. Forms a heterohexamer composed of alternating toxin and antitoxin homodimers MazF₂-MazE₂-MazF₂. The binding site of MazE and ssRNA or ssDNA are largely overlapping; the presence of only 1 MazE molecule inhibits mRNA endoribonuclease activity. Binds to EDF but not a mutated EDF (NNGNN) (PubMed:21419338).5 Publications

GO - Molecular functionⁱ

protein homodimerization activity
Source: CAFA
Inferred from direct assayⁱ
- 12718874

View the complete GO annotation on QuickGO ...

Protein-protein interaction databases

BioGridⁱ	4262300, 13 interactors
ComplexPortalⁱ	CPX-1086 MazEF toxin-antitoxin complex
IntActⁱ	P0AE70, 2 interactors
STRINGⁱ	316385.ECDH10B_2949

Chemistry databases

BindingDBⁱ	P0AE70

BindingDBⁱ

P0AE70

Structureⁱ

Secondary structure

Legend: HelixTurnBeta strandPDB Structure known for this area

Feature key	Position(s)	DescriptionActions	Length
Beta strandⁱ	11 – 15	Combined sources	5
Turnⁱ	19 – 22	Combined sources	4
Beta strandⁱ	29 – 33	Combined sources	5
Helixⁱ	37 – 43	Combined sources	7
Beta strandⁱ	46 – 53	Combined sources	8
Beta strandⁱ	61 – 63	Combined sources	3
Beta strandⁱ	66 – 69	Combined sources	4
Beta strandⁱ	72 – 74	Combined sources	3
Helixⁱ	75 – 77	Combined sources	3
Beta strandⁱ	79 – 81	Combined sources	3
Helixⁱ	83 – 86	Combined sources	4
Beta strandⁱ	89 – 93	Combined sources	5
Helixⁱ	96 – 110	Combined sources	15

Show more details

3D structure databases

Database of protein disorder More...DisProtⁱ	DP00299
ProteinModelPortalⁱ	P0AE70
SMRⁱ	P0AE70
ModBaseⁱ	Search...
MobiDBⁱ	Search...

Miscellaneous databases

EvolutionaryTraceⁱ	P0AE70

EvolutionaryTraceⁱ

P0AE70

Family & Domainsⁱ

Region

Feature key	Position(s)	DescriptionActions	Graphical view	Length
Regionⁱ	17 – 28	Loop 1, participates in catalytic activity1 PublicationAdd BLAST		12
Regionⁱ	53 – 61	Loop 2, involved in substrate recognition1 Publication		9

Domainⁱ

Loop 1 (residues 17-28) effects catalytic activity while recognition of the ACA cleavage site is influenced by loop 2 (residues 53-61). Alterations of loop 2 generate new cleavage sites in addition to retaining the original cleavage site.1 Publication

Sequence similaritiesⁱ

Belongs to the PemK/MazF family.Curated

Phylogenomic databases

eggNOGⁱ	ENOG4105MZG Bacteria COG2337 LUCA
HOGENOMⁱ	HOG000290185
InParanoidⁱ	P0AE70
KEGG Orthology (KO) More...KOⁱ	K07171
OMAⁱ	QIKGYPF
PhylomeDBⁱ	P0AE70

Family and domain databases

Gene3Dⁱ	2.30.30.110, 1 hit
InterProⁱ	View protein in InterPro IPR003477 PemK-like IPR011067 Plasmid_toxin/cell-grow_inhib
PANTHERⁱ	PTHR33988 PTHR33988, 1 hit
Pfam protein domain database More...Pfamⁱ	View protein in Pfam PF02452 PemK_toxin, 1 hit

Sequenceⁱ

Sequence statusⁱ: Complete.

P0AE70-1 [UniParc]FASTA Add to basket

« Hide

        10         20         30         40         50
MVSRYVPDMG DLIWVDFDPT KGSEQAGHRP AVVLSPFMYN NKTGMCLCVP 
        60         70         80         90        100
CTTQSKGYPF EVVLSGQERD GVALADQVKS IAWRARGATK KGTVAPEELQ 
       110 
LIKAKINVLI G

Length:111

Mass (Da):12,098

Last modified:December 6, 2005 - v1

Checksum:ⁱ1579C867DD6B96AC

GO

Sequence databases

Select the link destinations: EMBLⁱ GenBankⁱ DDBJⁱ Links Updated	D16450 Genomic DNA Translation: BAA03918.1 J04039 Unassigned DNA Translation: AAA03239.1 U29580 Genomic DNA Translation: AAA69292.1 U00096 Genomic DNA Translation: AAC75824.1 AP009048 Genomic DNA Translation: BAE76856.1
PIRⁱ	B49339
NCBI Reference Sequences More...RefSeqⁱ	NP_417262.1, NC_000913.3 WP_000254738.1, NZ_LN832404.1

Genome annotation databases

EnsemblBacteriaⁱ	AAC75824; AAC75824; b2782 BAE76856; BAE76856; BAE76856
GeneIDⁱ	947252
KEGGⁱ	ecj:JW2753 eco:b2782
PATRICⁱ	fig\|1411691.4.peg.3953

Protein	Similar proteins		Species	Score	Length	Source
P0AE70	Endoribonuclease MazF		ECO57		111	UniRef100_P0AE71
PemK domain containing protein		TRITR		111
mRNA interferase MazF		SHIBO		111
PemK-like cell growth regulatory protein ChpA		ECOLX		111
mRNA interferase MazF		SHIDY		111
+67

Protein	Similar proteins		Species	Score	Length	Source
P0AE70	Endoribonuclease MazF		ECO57		111	UniRef90_P0AE71
PemK domain containing protein		TRITR		111
mRNA interferase MazF		SHIBO		111
PemK-like cell growth regulatory protein ChpA		ECOLX		111
mRNA interferase MazF		SHIDY		111
+243

Protein	Similar proteins		Species	Score	Length	Source
P0AE70	Endoribonuclease MazF		ECO57		111	UniRef50_P0AE71
PemK domain containing protein		TRITR		111
mRNA interferase MazF		SHIBO		111
PemK-like cell growth regulatory protein ChpA		ECOLX		111
mRNA interferase MazF		SHIDY		111
+450

Entry informationⁱ

Entry nameⁱ	MAZF_ECOLI
Accessionⁱ	P0AE70Primary (citable) accession number: P0AE70 Secondary accession number(s): P33645, Q2MA50
Entry historyⁱ	Integrated into UniProtKB/Swiss-Prot:	December 6, 2005
	Last sequence update:	December 6, 2005
	Last modified:	September 12, 2018
	This is version 101 of the entry and version 1 of the sequence. See complete history.
Entry statusⁱ	Reviewed (UniProtKB/Swiss-Prot)
Annotation program	Prokaryotic Protein Annotation Program

Miscellaneousⁱ

Keywords - Technical termⁱ

3D-structure, Complete proteome, Reference proteome

UniProtKB

UniParc

Help

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Supporting data

UniProtKB - P0AE70 (MAZF_ECOLI)

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Endoribonuclease toxin MazF

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<p>This section provides any useful information about the protein, mostly biological knowledge.<p><a href='/help/function_section' target='_top'>More...</a></p>Functioni

Caution

<p>The <a href="http://www.geneontology.org/">Gene Ontology (GO)</a> project provides a set of hierarchical controlled vocabulary split into 3 categories:<p><a href='/help/gene_ontology' target='_top'>More...</a></p>GO - Molecular functioni

GO - Biological processi

Enzyme and pathway databases

<p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence.<p><a href='/help/names_and_taxonomy_section' target='_top'>More...</a></p>Names & Taxonomyi

Organism-specific databases

<p>This section provides information on the location and the topology of the mature protein in the cell.<p><a href='/help/subcellular_location_section' target='_top'>More...</a></p>Subcellular locationi

GO - Cellular componenti

<p>This section provides information on the disease(s) and phenotype(s) associated with a protein.<p><a href='/help/pathology_and_biotech_section' target='_top'>More...</a></p>Pathology & Biotechi

<p>This subsection of the ‘Pathology and Biotech’ section describes the use of a specific protein in the biotechnological industry.<p><a href='/help/biotechnological_use' target='_top'>More...</a></p>Biotechnological usei

Mutagenesis

Chemistry databases

<p>This section describes post-translational modifications (PTMs) and/or processing events.<p><a href='/help/ptm_processing_section' target='_top'>More...</a></p>PTM / Processingi

Molecule processing

Proteomic databases

<p>This section provides information on the expression of a gene at the mRNA or protein level in cells or in tissues of multicellular organisms.<p><a href='/help/expression_section' target='_top'>More...</a></p>Expressioni

<p>This section provides information on the quaternary structure of a protein and on interaction(s) with other proteins or protein complexes.<p><a href='/help/interaction_section' target='_top'>More...</a></p>Interactioni

GO - Molecular functioni

Protein-protein interaction databases

Chemistry databases

<p>This section provides information on the tertiary and secondary structure of a protein.<p><a href='/help/structure_section' target='_top'>More...</a></p>Structurei

Secondary structure

3D structure databases

Miscellaneous databases

<p>This section provides information on sequence similarities with other proteins and the domain(s) present in a protein.<p><a href='/help/family_and_domains_section' target='_top'>More...</a></p>Family & Domainsi

Region

<p>This subsection of the ‘Family and domains’ section provides information about the sequence similarity with other proteins.<p><a href='/help/sequence_similarities' target='_top'>More...</a></p>Sequence similaritiesi

Phylogenomic databases

Family and domain databases

Sequence databases

Genome annotation databases

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<p>This section contains any relevant information that doesn’t fit in any other defined sections<p><a href='/help/miscellaneous_section' target='_top'>More...</a></p>Miscellaneousi

Keywords - Technical termi

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Functionⁱ

GO - Molecular functionⁱ

GO - Biological processⁱ

Names & Taxonomyⁱ

Subcellular locationⁱ

GO - Cellular componentⁱ

Pathology & Biotechⁱ

Biotechnological useⁱ

PTM / Processingⁱ

Expressionⁱ

Interactionⁱ

GO - Molecular functionⁱ

Structureⁱ

Family & Domainsⁱ

Sequence similaritiesⁱ

Entry informationⁱ

Miscellaneousⁱ

Keywords - Technical termⁱ