AbiG system

traitmech:000306 · CLASS · PROPOSED

An abortive infection system in which an organism possesses a two-gene abiG locus with abiGi and abiGii open reading frames, exemplified by the Lactococcus lactis subsp. cremoris UC653 plasmid pCI750 locus that restricts lactococcal phages without blocking phage DNA replication and is represented by the DefenseFinder AbiG__AbiGi and AbiG__AbiGii profiles.

Trait evidence (12)

DOI:10.1128/aem.62.9.3075-3082.1996
AbiG is an abortive infection (Abi) mechanism encoded by the conjugative plasmid pCI750 originally isolated from Lactococcus lactis subsp. cremoris UC653

O'Connor et al. identify AbiG as an abortive-infection mechanism encoded by the UC653 pCI750 plasmid.
DOI:10.1128/aem.62.9.3075-3082.1996
Insensitivity conferred by this Abi manifested itself as complete resistance to phi 712 (936 phage species) with only partial resistance to phi c2 (c2 species)

O'Connor et al. show that AbiG restricts tested lactococcal phages with species-dependent strength.
DOI:10.1128/aem.62.9.3075-3082.1996
The smallest subclone of pCI750 which expressed the Abi phenotype contained a 3.5-kb insert which encoded two potential open reading frames

O'Connor et al. localize AbiG activity to a pCI750 subclone carrying two predicted coding sequences.
DOI:10.1128/aem.62.9.3075-3082.1996
abiGi (750 bp) and abiGii (1,194 bp) were separated by 2 bp and appeared to share a single promoter upstream of abiGi

O'Connor et al. support abiGi and abiGii as the paired open reading frames of the AbiG locus.
DOI:10.1128/aem.62.9.3075-3082.1996
The mechanism did not inhibit phage DNA replication

O'Connor et al. rule out phage DNA replication as the blocked step in the original AbiG characterization.
DOI:10.1128/aem.65.1.330-335.1999
The abortive infection system AbiG is encoded by the lactococcal plasmid pCI750

The follow-up O'Connor et al. study reiterates AbiG as a pCI750-encoded lactococcal abortive-infection system.
DOI:10.1128/aem.65.1.330-335.1999
The abiG locus (consisting of two genes, abiGi and abiGii) was examined by Northern blot analysis, revealing two transcripts of approximately 2.8 and 1.5 kb which were homologous to the two gene-specific probes

O'Connor et al. confirm the abiGi/abiGii two-gene locus at the transcript level.
DOI:10.1128/aem.65.1.330-335.1999
Examination of phage sk1 RNA synthesis demonstrated that both the subcloned AbiG and, to a greater extent, pCI750 inhibited this process

O'Connor et al. connect the AbiG subclone to inhibited sk1 phage RNA synthesis.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md
AbiG | 10\.1016/j\.mib\.2005\.06\.006 | Phage abortive infection in lactococci: variations on a theme

The DefenseFinder article registry maps the named AbiG model namespace to a lactococcal abortive-infection review.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv
AbiG AbiG 2 2 AbiG__AbiGi, AbiG__AbiGii

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

The DefenseFinder HMM inventory records AbiG__AbiGi under the AbiG model namespace.
https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md
| AbiG__AbiGii | AbiG__AbiGii | AbiG | Custom | 20 |

The DefenseFinder HMM inventory records AbiG__AbiGii under the AbiG model namespace.

AbiG inhibits lactococcal phage RNA synthesis

Conservative system-level sketch linking an abiGi/abiGii locus to AbiG antiphage activity, inhibited phage RNA synthesis, restricted lactococcal phage propagation, and abortive-infection system possession without asserting AbiG's unresolved primary target.

NONMECHANISTIC · The graph captures AbiG as a named DefenseFinder two-profile abortive-infection system whose pCI750 prototype restricts phi 712, partially restricts phi c2, and inhibits phage sk1 and late c2 RNA synthesis while leaving the phage trigger, AbiGi and AbiGii molecular functions, cellular target, growth-arrest or cell-death route, and phage escape routes unresolved.

Edge evidence

abiG locus contributes to AbiG antiphage activity RO:0002326
The pCI750 abiG locus carries abiGi and abiGii open reading frames, and DefenseFinder models AbiG as a two-profile system requiring both AbiG components.
- DOI:10.1128/aem.62.9.3075-3082.1996 The smallest subclone of pCI750 which expressed the Abi phenotype contained a 3.5-kb insert which encoded two potential open reading frames O'Connor et al. localize the AbiG phenotype to a two-ORF pCI750 subclone.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv AbiG AbiG 2 2 AbiG__AbiGi, AbiG__AbiGii The DefenseFinder rules table models AbiG as a two-component system requiring the AbiG__AbiGi and AbiG__AbiGii profiles.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | AbiG__AbiGi | AbiG__AbiGi | AbiG | Custom | 20 | The DefenseFinder HMM inventory records AbiG__AbiGi under the AbiG model namespace.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md | AbiG__AbiGii | AbiG__AbiGii | AbiG | Custom | 20 | The DefenseFinder HMM inventory records AbiG__AbiGii under the AbiG model namespace.
AbiG antiphage activity mitigates phage RNA synthesis METPO:2007407
AbiG antiphage activity inhibits RNA synthesis by tested sensitive lactococcal phages.
- DOI:10.1128/aem.65.1.330-335.1999 Examination of phage sk1 RNA synthesis demonstrated that both the subcloned AbiG and, to a greater extent, pCI750 inhibited this process O'Connor et al. show that the AbiG subclone inhibits phage sk1 RNA synthesis.
AbiG antiphage activity contributes to restricted phage propagation RO:0002326
AbiG activity restricts propagation by phi 712 and partially restricts phi c2.
- DOI:10.1128/aem.62.9.3075-3082.1996 Insensitivity conferred by this Abi manifested itself as complete resistance to phi 712 (936 phage species) with only partial resistance to phi c2 (c2 species) O'Connor et al. measure complete or partial resistance from the AbiG mechanism for tested lactococcal phages.
restricted phage propagation confers AbiG system METPO:2007700
Restriction of lactococcal phage propagation realizes the AbiG abortive-infection trait.
- DOI:10.1128/aem.62.9.3075-3082.1996 AbiG is an abortive infection (Abi) mechanism encoded by the conjugative plasmid pCI750 O'Connor et al. classify AbiG as a pCI750 abortive-infection mechanism.
- https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md AbiG | 10\.1016/j\.mib\.2005\.06\.006 | Phage abortive infection in lactococci: variations on a theme The DefenseFinder article registry maps the named AbiG model namespace to a lactococcal abortive-infection review.
AbiG system is a abortive infection system rdfs:subClassOf
AbiG system possession is an abortive-infection-system trait.
- DOI:10.1128/aem.65.1.330-335.1999 The abortive infection system AbiG is encoded by the lactococcal plasmid pCI750 O'Connor et al. explicitly place AbiG in the abortive-infection class of phage defense.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1128/aem.62.9.3075-3082.1996

Parent traits (1)

abortive infection system traitmech:000214

Synonyms (1)

AbiG RELATED_SYNONYM · DOI:10.1128/aem.62.9.3075-3082.1996

kg-microbe context

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

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

Lactococcus lactis NCBITaxon:1358 DOI:10.1128/aem.62.9.3075-3082.1996 O'Connor et al. characterized AbiG from conjugative plasmid pCI750, originally isolated from Lactococcus lactis subsp. cremoris UC653, and localized the abortive-infection phenotype to the abiGi/abiGii locus.

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 AbiG phage trigger, AbiGi and AbiGii molecular functions, and primary arrest target before minting narrower AbiG mechanism children.

KNOWLEDGE GAP OPEN abig-primary-target-gap · raised by codex · 2026-09-20

Attached to causal_graphs#abig_inhibits_lactococcal_phage_rna_synthesis

O'Connor et al. support AbiG as a named lactococcal abortive-infection system encoded by two adjacent pCI750 open reading frames, and DefenseFinder represents AbiG with a two-profile rule. The 1999 transcription study connects AbiG to inhibited phage sk1 and late c2 RNA synthesis, but it explicitly leaves unresolved whether transcription is the system's primary target or a secondary effect.

Evidence

DOI:10.1128/aem.65.1.330-335.1999
AbiG inhibits phage sk1 and late c2 RNA synthesis; however, whether this process of transcription is the primary target of the system or a secondary effect remains to be determined

Curation history

2026-09-20T09:16:00Z · MINTED_TRAITMECH_ID · codex
Minted AbiG 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, or prior proposal record; the replacement placeholder is reserved in proposals/metpo_traitmech_v183.
2026-09-20T10:19:00Z · STANDARDIZED_CAUSAL_NODE_LABEL · codex
Reused the existing restricted phage propagation causal-node label after PR review found that the lactococcal-specific label duplicated the taxon-neutral GENOMICS phage-defense node.