TOXN_PECAT
ID TOXN_PECAT Reviewed; 171 AA.
AC B8X8Z0;
DT 29-APR-2015, integrated into UniProtKB/Swiss-Prot.
DT 03-MAR-2009, sequence version 1.
DT 25-MAY-2022, entry version 38.
DE RecName: Full=Endoribonuclease ToxN {ECO:0000303|PubMed:21240270};
DE Short=EndoRNase {ECO:0000303|PubMed:21240270};
DE EC=3.1.-.-;
DE AltName: Full=Toxin ToxN {ECO:0000303|PubMed:19124776};
GN Name=toxN {ECO:0000303|PubMed:19124776};
OS Pectobacterium atrosepticum (Erwinia carotovora subsp. atroseptica).
OG Plasmid pECA1039.
OC Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales;
OC Pectobacteriaceae; Pectobacterium.
OX NCBI_TaxID=29471;
RN [1]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, INDUCTION, DISRUPTION
RP PHENOTYPE, AND EXPRESSION IN E.COLI AND P.ATROSEPTICUM STRAIN 1043.
RC STRAIN=SCRI 1039 / ATCC BAA-673; PLASMID=pECA1039;
RX PubMed=19124776; DOI=10.1073/pnas.0808832106;
RA Fineran P.C., Blower T.R., Foulds I.J., Humphreys D.P., Lilley K.S.,
RA Salmond G.P.;
RT "The phage abortive infection system, ToxIN, functions as a protein-RNA
RT toxin-antitoxin pair.";
RL Proc. Natl. Acad. Sci. U.S.A. 106:894-899(2009).
RN [2]
RP FUNCTION, INDUCTION, MUTAGENESIS OF TYR-10; LYS-20; PHE-35; GLY-37; TYR-47;
RP SER-53; LYS-116 AND GLU-154, AND EXPRESSION IN E.COLI AND P.ATROSEPTICUM
RP STRAIN 1043.
RC STRAIN=SCRI 1039 / ATCC BAA-673; PLASMID=pECA1039;
RX PubMed=19633081; DOI=10.1128/jb.00720-09;
RA Blower T.R., Fineran P.C., Johnson M.J., Toth I.K., Humphreys D.P.,
RA Salmond G.P.;
RT "Mutagenesis and functional characterization of the RNA and protein
RT components of the toxIN abortive infection and toxin-antitoxin locus of
RT Erwinia.";
RL J. Bacteriol. 191:6029-6039(2009).
RN [3]
RP FUNCTION, AND SUBUNIT.
RC STRAIN=SCRI 1039 / ATCC BAA-673; PLASMID=pECA1039;
RX PubMed=23267117; DOI=10.1073/pnas.1216039110;
RA Short F.L., Pei X.Y., Blower T.R., Ong S.L., Fineran P.C., Luisi B.F.,
RA Salmond G.P.;
RT "Selectivity and self-assembly in the control of a bacterial toxin by an
RT antitoxic noncoding RNA pseudoknot.";
RL Proc. Natl. Acad. Sci. U.S.A. 110:E241-E249(2013).
RN [4]
RP VIRAL ESCAPE MECHANISM, AND INDUCTION.
RC STRAIN=SCRI 1039 / ATCC BAA-673; PLASMID=pECA1039;
RX PubMed=23109916; DOI=10.1371/journal.pgen.1003023;
RA Blower T.R., Evans T.J., Przybilski R., Fineran P.C., Salmond G.P.;
RT "Viral evasion of a bacterial suicide system by RNA-based molecular mimicry
RT enables infectious altruism.";
RL PLoS Genet. 8:E1003023-E1003023(2012).
RN [5]
RP X-RAY CRYSTALLOGRAPHY (2.55 ANGSTROMS) IN COMPLEX WITH ANTITOXIN TOXI,
RP SUBUNIT, MUTAGENESIS OF TYR-29; LYS-33; THR-52; SER-53; LYS-55; HIS-58 AND
RP GLN-117, AND RNA-BINDING.
RC STRAIN=SCRI 1039 / ATCC BAA-673; PLASMID=pECA1039;
RX PubMed=21240270; DOI=10.1038/nsmb.1981;
RA Blower T.R., Pei X.Y., Short F.L., Fineran P.C., Humphreys D.P.,
RA Luisi B.F., Salmond G.P.;
RT "A processed noncoding RNA regulates an altruistic bacterial antiviral
RT system.";
RL Nat. Struct. Mol. Biol. 18:185-190(2011).
CC -!- FUNCTION: Toxic component of a type III toxin-antitoxin (TA) system. An
CC endoribonuclease which is active independently of the ribosome,
CC cleaving between the second and third A of AAA(U/G) sequences, although
CC not all occurrences of this tetranucleotide are cleaved
CC (PubMed:23267117). Digests many mRNA species, including its own
CC transcript and its cognate antitoxin RNA ToxI. ToxI has 5.5 nearly
CC identical 36 nucleotide-long repeats (a single repeat neutralizes the
CC toxin in vivo); a single repeat folds into a pseudoknot which binds the
CC toxin (PubMed:21240270). The ToxI precursor RNA is a preferential
CC target in vivo and is progressively degraded to single repeat lengths
CC as ToxN-ToxI complex self-assembly occurs (PubMed:23267117). In vivo
CC expression of ToxI antitoxin inhibits endonuclease activity of ToxN
CC (PubMed:23267117). The toxin alone inhibits growth when expressed in
CC E.coli without causing cell lysis; this bacteriostatic effect is
CC neutralized by cognate RNA antitoxin ToxI (PubMed:19124776,
CC PubMed:23267117). Non-cognate antitoxin RNA from B.thuringiensis does
CC not inhibit this toxin (PubMed:23267117). The RNA antitoxin is less
CC stable than the proteinaceous toxin; synthesis of ToxI in the absence
CC of new ToxN synthesis restores growth and also detectable accumulation
CC of the ToxN protein (PubMed:19124776). Negatively regulates its own
CC operon in complex with ToxI (PubMed:19633081). The toxin-antitoxin
CC system functions in plasmid maintenance (a plasmid addiction system)
CC (PubMed:23267117). {ECO:0000269|PubMed:19124776,
CC ECO:0000269|PubMed:19633081, ECO:0000269|PubMed:21240270,
CC ECO:0000269|PubMed:23267117}.
CC -!- FUNCTION: The TA system protects P.atrosepticum strain 1043 against
CC phage phiM1 and phiA2, E.coli against some but not all coliphages and
CC S.marcescens against some bacteriophages, causing an abortive infection
CC (Abi phenotype) (PubMed:19124776). Also protects P.atrosepticum strain
CC 1043 against phage phiTE; phage that escape Abi and grow in this
CC bacterium have evolved a pseudo-ToxI RNA by expanding a pre-existing
CC sequence similar to the bona fide ToxI repeats (PubMed:23109916).
CC {ECO:0000269|PubMed:19124776, ECO:0000269|PubMed:23109916}.
CC -!- SUBUNIT: One ToxN monomer binds to a 36-nt-long single repeat of the
CC ToxI RNA; this complex forms a triangular heterohexameric complex with
CC ToxN connected by the ToxI RNA to another toxin molecule. The ToxI
CC repeat forms a pseudoknot which occludes the toxin active site.
CC Interaction of ToxI with ToxN partially inhibits the latter's
CC endoribonuclease activity in vitro (PubMed:21240270). The complex self-
CC assembles in vitro with either full-length or processed single repeats;
CC during the process the precursor is processed (PubMed:23267117).
CC {ECO:0000269|PubMed:21240270, ECO:0000269|PubMed:23267117}.
CC -!- INTERACTION:
CC B8X8Z0; B8X8Z0: toxN; NbExp=2; IntAct=EBI-15904863, EBI-15904863;
CC -!- INDUCTION: Part of the toxIN operon. The operon is repressed by ToxI
CC and ToxN together, but not by ToxI alone (ToxN alone cannot be tested
CC as it is toxic) (PubMed:19633081). About 90% of transcripts terminate
CC after toxI, approximately 10% include toxN (PubMed:19124776).
CC Constitutively expressed in P.atrosepticum strain 1043 in the presence
CC and absence of phage phiTE infection (at protein level)
CC (PubMed:23109916). {ECO:0000269|PubMed:19124776,
CC ECO:0000269|PubMed:19633081, ECO:0000269|PubMed:23109916}.
CC -!- DISRUPTION PHENOTYPE: Loss of resistance to phage phiM1 and phiA2.
CC {ECO:0000269|PubMed:19124776}.
CC -!- SIMILARITY: Belongs to the ToxN/AbiQ toxin family. {ECO:0000305}.
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DR EMBL; FJ176937; ACK87011.1; -; Genomic_DNA.
DR RefSeq; WP_012609144.1; NC_011767.1.
DR RefSeq; YP_002429170.1; NC_011767.1.
DR PDB; 2XD0; X-ray; 3.00 A; A/B/E/X/Y/Z=1-171.
DR PDB; 2XDB; X-ray; 2.55 A; A=1-171.
DR PDB; 2XDD; X-ray; 3.20 A; A/B/E=1-171.
DR PDBsum; 2XD0; -.
DR PDBsum; 2XDB; -.
DR PDBsum; 2XDD; -.
DR AlphaFoldDB; B8X8Z0; -.
DR SMR; B8X8Z0; -.
DR DIP; DIP-59074N; -.
DR GO; GO:0004521; F:endoribonuclease activity; IDA:UniProtKB.
DR GO; GO:0042802; F:identical protein binding; IPI:IntAct.
DR GO; GO:0003723; F:RNA binding; IDA:UniProtKB.
DR GO; GO:0051607; P:defense response to virus; IDA:UniProtKB.
DR GO; GO:0045892; P:negative regulation of transcription, DNA-templated; IDA:UniProtKB.
DR GO; GO:0006276; P:plasmid maintenance; IMP:UniProtKB.
DR InterPro; IPR025911; ToxN/AbiQ_toxin.
DR Pfam; PF13958; ToxN_toxin; 1.
PE 1: Evidence at protein level;
KW 3D-structure; Antiviral defense; Endonuclease; Hydrolase; Nuclease;
KW Plasmid; RNA-binding; Toxin-antitoxin system; Transcription;
KW Transcription regulation.
FT CHAIN 1..171
FT /note="Endoribonuclease ToxN"
FT /id="PRO_0000432892"
FT MUTAGEN 10
FT /note="Y->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 20
FT /note="K->A: Still confers phiA2 resistance, toxic in
FT E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 20
FT /note="K->E: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 29
FT /note="Y->A: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 33
FT /note="K->A: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 35
FT /note="F->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 37
FT /note="G->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 47
FT /note="Y->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 52
FT /note="T->A: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 53
FT /note="S->A: No longer confers phiA2 resistance, not toxic
FT in E.coli (Ref.2). Alters but does not inhibit RNase site-
FT specificity (Ref.3)."
FT /evidence="ECO:0000269|PubMed:19633081,
FT ECO:0000269|PubMed:21240270"
FT MUTAGEN 55
FT /note="K->A: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 58
FT /note="H->L: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 64
FT /note="S->A: Still confers phiA2 resistance, toxic in
FT E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 87
FT /note="K->A: Still confers phiA2 resistance, toxic in
FT E.coli but colonies are smaller."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 115
FT /note="Y->A: Still confers phiM1 or phiS61 resistance,
FT toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 116
FT /note="K->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 117
FT /note="Q->E: No longer confers phiM1 or phiS61 resistance,
FT not toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 122
FT /note="R->A: Still toxic in E.coli."
FT /evidence="ECO:0000269|PubMed:21240270"
FT MUTAGEN 142
FT /note="G->A: Still confers phiA2 resistance, toxic in
FT E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 148
FT /note="C->A: Still confers phiA2 resistance, toxic in
FT E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT MUTAGEN 154
FT /note="E->A: No longer confers phiA2 resistance, not toxic
FT in E.coli."
FT /evidence="ECO:0000269|PubMed:19633081"
FT STRAND 3..6
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 8..17
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 35..42
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 45..52
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 56..60
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 69..73
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 76..84
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 86..88
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 90..92
FT /evidence="ECO:0007829|PDB:2XD0"
FT HELIX 94..96
FT /evidence="ECO:0007829|PDB:2XDB"
FT STRAND 97..99
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 102..104
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 109..123
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 125..140
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 150..156
FT /evidence="ECO:0007829|PDB:2XDB"
FT HELIX 157..159
FT /evidence="ECO:0007829|PDB:2XDB"
SQ SEQUENCE 171 AA; 19702 MW; 79A84807F1378950 CRC64;
MKFYTISSKY IEYLKEFDDK VPNSEDPTYQ NPKAFIGIVL EIQGHKYLAP LTSPKKWHNN
VKESSLSCFK LHENGVPENQ LGLINLKFMI PIIEAEVSLL DLGNMPNTPY KRMLYKQLQF
IRANSDKIAS KSDTLRNLVL QGKMQGTCNF SLLEEKYRDF GKEAEDTEEG E
