MqsRAC system

traitmech:000368 · CLASS · PROPOSED

A phage defense system in which an organism possesses a tripartite MqsRAC toxin-antitoxin-chaperone locus represented by DefenseFinder as a two-profile model requiring MqsRAC__mqsC and MqsRAC__mqsR.

Trait evidence (8)

PMID:38054715
Therefore, our results are important since we show for the first time that a phage-defense system, the MqsRAC toxin/antitoxin system, allows the host to survive infection by forming persister cells, rather than inducing cell suicide.

Fernandez-Garcia et al. support MqsRAC as a phage-defense system whose outcome is host survival through persister-cell formation rather than cell suicide.
PMID:38054715
Moreover, we demonstrate that the MqsRAC system works in concert with restriction/modification systems.

Fernandez-Garcia et al. connect the MqsRAC system to restriction/modification systems during phage inhibition.
DOI:10.1128/spectrum.03388-23
the tripartite system MqsR (RNase toxin)/MqsA (antitoxin)/MqsC (SecB-type chaperone)

Fernandez-Garcia et al. describe MqsR/MqsA/MqsC as a tripartite toxin-antitoxin-chaperone phage-exclusion system from Escherichia coli C496_10.
DOI:10.1128/spectrum.03388-23
We found there was a 2,100 to a 5,000-fold reduction in the EOP with phage T2 when the cells produced MqsR/MqsA/MqsC

Fernandez-Garcia et al. support MqsRAC-mediated reduction of T2 efficiency of plating.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md
MqsRAC | 10\.1101/2022\.05\.12\.491691 | Mapping the landscape of anti-phage defense mechanisms in the E\. coli pangenome

The DefenseFinder article registry maps the named MqsRAC system to Vassallo et al.'s E. coli pangenome phage-defense screen.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv
MqsRAC MqsRAC 2 2 MqsRAC__mqsC, MqsRAC__mqsR

The DefenseFinder rules table models MqsRAC as a two-profile system requiring the MqsRAC__mqsC and MqsRAC__mqsR profiles.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md
| MqsRAC__mqsC | MqsRAC__mqsC | MqsRAC | Custom | 20 |

The DefenseFinder HMM inventory records MqsRAC__mqsC under MqsRAC.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md
| MqsRAC__mqsR | MqsRAC__mqsR | MqsRAC | Custom | 20 |

The DefenseFinder HMM inventory records MqsRAC__mqsR under MqsRAC.

MqsRAC loci support T2 phage inhibition

Conservative system-level sketch linking possession of an MqsRAC locus to persister-cell formation and T2 inhibition without asserting a universal phage trigger, lethal abortive-infection route, or exact MqsRAC profile-to-activity mapping.

NONMECHANISTIC · The graph captures MqsRAC as a named DefenseFinder two-profile phage-defense system while leaving natural phage breadth, upstream MqsRAC activation logic, the exact relationship between the two DefenseFinder profiles and the tripartite MqsR/MqsA/MqsC locus, and cooperating restriction/modification contexts unresolved.

Edge evidence

MqsRAC locus contributes to MqsRAC-dependent persister cell formation RO:0002326
Fernandez-Garcia et al. show that the MqsR/MqsA/MqsC toxin-antitoxin-chaperone system can promote persister-cell formation during T2 attack, and DefenseFinder models MqsRAC as a two-profile system.
- PMID:38054715 Therefore, our results are important since we show for the first time that a phage-defense system, the MqsRAC toxin/antitoxin system, allows the host to survive infection by forming persister cells, rather than inducing cell suicide. Fernandez-Garcia et al. connect the MqsRAC system to persister-cell formation.
- DOI:10.1128/spectrum.03388-23 the tripartite system MqsR (RNase toxin)/MqsA (antitoxin)/MqsC (SecB-type chaperone) Fernandez-Garcia et al. identify the system components as MqsR, MqsA, and MqsC.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md MqsRAC | 10\.1101/2022\.05\.12\.491691 | Mapping the landscape of anti-phage defense mechanisms in the E\. coli pangenome The DefenseFinder article registry maps the named MqsRAC system to Vassallo et al.'s E. coli pangenome phage-defense screen.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv MqsRAC MqsRAC 2 2 MqsRAC__mqsC, MqsRAC__mqsR The DefenseFinder rules table models MqsRAC as a two-profile system requiring the MqsRAC__mqsC and MqsRAC__mqsR profiles.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | MqsRAC__mqsC | MqsRAC__mqsC | MqsRAC | Custom | 20 | The DefenseFinder HMM inventory records MqsRAC__mqsC under MqsRAC.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | MqsRAC__mqsR | MqsRAC__mqsR | MqsRAC | Custom | 20 | The DefenseFinder HMM inventory records MqsRAC__mqsR under MqsRAC.
MqsRAC locus contributes to restriction/modification-assisted T2 inhibition RO:0002326
Fernandez-Garcia et al. report that the MqsR/MqsA/MqsC toxin-antitoxin-chaperone system works in concert with restriction/modification systems during T2 inhibition.
- DOI:10.1128/spectrum.03388-23 Therefore, MqsR/MqsA/MqsC works in concert with restriction/modification systems to inhibit T2 phage. Fernandez-Garcia et al. connect the MqsRAC system to restriction/modification activity during T2 inhibition.
MqsRAC-dependent persister cell formation confers MqsRAC system METPO:2007700
MqsRAC-dependent survival through persister-cell formation realizes the MqsRAC system trait.
- PMID:38054715 Therefore, our results are important since we show for the first time that a phage-defense system, the MqsRAC toxin/antitoxin system, allows the host to survive infection by forming persister cells, rather than inducing cell suicide. Fernandez-Garcia et al. report MqsRAC-dependent host survival through persister-cell formation rather than cell suicide.
restriction/modification-assisted T2 inhibition confers MqsRAC system METPO:2007700
MqsR/MqsA/MqsC-mediated T2 inhibition realizes the MqsRAC system trait.
- DOI:10.1128/spectrum.03388-23 We found there was a 2,100 to a 5,000-fold reduction in the EOP with phage T2 when the cells produced MqsR/MqsA/MqsC Fernandez-Garcia et al. report reduced T2 efficiency of plating in cells producing MqsR/MqsA/MqsC.
MqsRAC system is a phage defense system rdfs:subClassOf
MqsRAC system possession is a phage-defense-system trait.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md MqsRAC | 10\.1101/2022\.05\.12\.491691 | Mapping the landscape of anti-phage defense mechanisms in the E\. coli pangenome The DefenseFinder article registry maps the named MqsRAC system to Vassallo et al.'s E. coli pangenome phage-defense screen.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv MqsRAC MqsRAC 2 2 MqsRAC__mqsC, MqsRAC__mqsR The DefenseFinder rules table models MqsRAC as a two-profile system requiring the MqsRAC__mqsC and MqsRAC__mqsR profiles.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1128/spectrum.03388-23

Parent traits (1)

phage defense system traitmech:000209

Synonyms (4)

MqsRAC RELATED_SYNONYM · DOI:10.1128/spectrum.03388-23
MqsR/MqsA/MqsC RELATED_SYNONYM · DOI:10.1128/spectrum.03388-23
MqsRAC__mqsC RELATED_SYNONYM · https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md
MqsRAC__mqsR RELATED_SYNONYM · https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Discussions and Knowledge Gaps (1)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve MqsRAC natural phage breadth, phage-activation signals, the exact DefenseFinder profile-to-MqsR/MqsA/MqsC relationship, and cooperating restriction/modification contexts before minting narrower MqsRAC mechanism children.

KNOWLEDGE GAP OPEN mqsrac-breadth-and-profile-gap · raised by codex · 2026-09-22

Attached to causal_graphs#mqsrac_locus_promotes_persister_phage_defense

Fernandez-Garcia et al. support MqsR/MqsA/MqsC as an Escherichia coli C496_10 toxin-antitoxin-chaperone system that inhibits T2 phage through persister-cell formation and in concert with restriction/modification systems, while DefenseFinder models MqsRAC through MqsRAC__mqsC and MqsRAC__mqsR markers. Natural phage breadth, the phage signal that activates MqsRAC, MqsA coverage in the DefenseFinder model, and cooperating restriction/modification contexts remain unresolved.

Evidence

PMID:38054715
Moreover, we demonstrate that the MqsRAC system works in concert with restriction/modification systems.

Curation history

2026-09-22T15:02:00Z · MINTED_TRAITMECH_ID · codex
Minted MqsRAC system as a DOI-backed GENOMICS TraitRecord under phage defense system after an ignored-and-hidden duplicate review found no exact live TraitMech, METPO, history, or prior proposal record; the replacement placeholder is reserved in proposals/metpo_traitmech_v245.
2026-09-22T15:03:00Z · REVIEW_CANONICAL_EXAMPLE_EVIDENCE_GAP · codex
Reviewed the MqsRAC canonical_examples gap and left canonical_examples empty: the current evidence supports a MqsR/MqsA/MqsC system from Escherichia coli C496_10 expressed from its natural promoter in a K-12 host, but it does not cite a directly observed natural microbial taxon broad enough for a canonical example of endogenous MqsRAC system possession. No paid research was used.
2026-09-22T15:15:00Z · GRAPH_EDGE_DIRECTION_REVIEW · codex
Addressed issue #1258 by replacing the unsupported MqsRAC persister-cell formation to restriction/modification-assisted T2 inhibition edge with independent MqsRAC locus to restriction/modification-assisted T2 inhibition and MqsRAC-dependent persister formation to MqsRAC system trait edges.
2026-09-22T15:18:00Z · REVIEW_RESTRICTION_MODIFICATION_SPECIFICITY · codex
Addressed issue #1259 by generalizing unsupported McrBC-specific wording to restriction/modification-assisted T2 inhibition throughout the MqsRAC graph and discussion.