Pif system

traitmech:000323 · CLASS · PROPOSED

An abortive infection system in which an organism possesses an F-plasmid pif-family locus represented by the DefenseFinder Pif__PifA and Pif__PifC profiles and exemplified by the pif region that specifies abortive infection of T7 phage.

Trait evidence (7)

PMID:6096670
Molecular analysis of F plasmid pif region specifying abortive infection of T7 phage.

Cram et al. title the paper around F-plasmid pif-region specification of the T7 abortive-infection phenotype.
DOI:10.1007/BF00327934
We report the molecular cloning of the pif region of the F plasmid and its physical dissection by subcloning and deletion analysis.

Cram et al. cloned and deletion-mapped the F-plasmid pif region.
DOI:10.1007/BF00327934
Examination of the polypeptide products synthesized in maxicells by plasmids carrying defined pif sequences has shown that the region specifies at least two proteins of molecular weights 80,000 and 40,000, the genes for which appear to lie in the same transcriptional unit.

Cram et al. support a multigene pif region without resolving a direct PifA or PifC molecular function.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md
Pif | 10\.1007/BF00327934 | Molecular analysis of F plasmid pif region specifying abortive infection of T7 phage

The DefenseFinder article registry maps the named Pif model namespace to the F-plasmid pif-region molecular analysis paper.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv
Pif Pif 2 2 Pif__PifA, Pif__PifC

The DefenseFinder rules table models Pif as a two-component system requiring both the Pif__PifA and Pif__PifC profiles.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md
| Pif__PifA | Pif__PifA | Pif | Custom | 20 |

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

The DefenseFinder HMM inventory records Pif__PifC under Pif.

Pif locus specifies T7 abortive infection

Conservative system-level sketch linking an F-plasmid pif-family locus to T7 abortive infection and Pif-system possession without asserting the direct phage trigger, host-cell output, or PifA/PifC molecular targets.

NONMECHANISTIC · The graph captures Pif as a named DefenseFinder two-profile abortive-infection system whose F-plasmid prototype specifies T7 abortive infection. It leaves the direct T7 trigger, PifA and PifC molecular functions, host-cell output, and phage escape route unresolved.

Edge evidence

pif locus contributes to T7 abortive infection RO:0002326
The F-plasmid pif region specifies T7 abortive infection, and DefenseFinder represents Pif with required PifA and PifC profiles.
- PMID:6096670 Molecular analysis of F plasmid pif region specifying abortive infection of T7 phage. Cram et al. frame the F-plasmid pif region as specifying T7 abortive infection.
- DOI:10.1007/BF00327934 the region specifies at least two proteins of molecular weights 80,000 and 40,000 Cram et al. observed two pif-region polypeptides in maxicells.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv Pif Pif 2 2 Pif__PifA, Pif__PifC The DefenseFinder rules table models Pif as a two-component system requiring both the Pif__PifA and Pif__PifC profiles.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | Pif__PifA | Pif__PifA | Pif | Custom | 20 | The DefenseFinder HMM inventory records Pif__PifA under Pif.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | Pif__PifC | Pif__PifC | Pif | Custom | 20 | The DefenseFinder HMM inventory records Pif__PifC under Pif.
T7 abortive infection confers Pif system METPO:2007700
F-plasmid-pif-specified T7 abortive infection realizes the Pif system trait.
- PMID:6096670 Molecular analysis of F plasmid pif region specifying abortive infection of T7 phage. Cram et al. support T7 abortive infection as the pif-region output.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md Pif | 10\.1007/BF00327934 | Molecular analysis of F plasmid pif region specifying abortive infection of T7 phage The DefenseFinder article registry maps the named Pif model namespace to the F-plasmid pif-region molecular analysis paper.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1007/BF00327934

Parent traits (1)

abortive infection system traitmech:000214

Synonyms (1)

Pif RELATED_SYNONYM · https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.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 the direct T7 trigger, PifA and PifC molecular functions, host-cell output, and phage escape routes before minting narrower Pif mechanism children.

KNOWLEDGE GAP OPEN pif-output-gap · raised by codex · 2026-09-21

Attached to causal_graphs#pif_locus_specifies_t7_abortive_infection

Cram et al. support an F-plasmid pif-region abortive-infection system that maps to a two-profile DefenseFinder model, but the direct T7 trigger, the molecular functions of PifA and PifC, the host-cell growth-arrest or cell-death output, and phage escape routes remain unresolved.

Curation history

2026-09-21T01:30:12Z · MINTED_TRAITMECH_ID · codex
Minted Pif system as a DOI-backed GENOMICS TraitRecord under the abortive infection system parent 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_v200.
2026-09-21T01:30:13Z · REVIEW_CANONICAL_EXAMPLE_EVIDENCE_GAP · codex
Reviewed canonical example evidence while minting Pif system and left canonical_examples empty: the Cram et al. prototype supports an F-plasmid pif region that specifies T7 abortive infection and the pinned DefenseFinder registry maps a two-profile Pif namespace, but the available curation sources do not identify a natural organism instance with a directly observed Pif locus. No paid research was used.