CBASS system

traitmech:000212 · CLASS · PROPOSED

A genomics trait describing possession of a cyclic-oligonucleotide-based antiphage signaling locus in which an oligonucleotide cyclase produces cyclic oligonucleotide signals during phage infection that activate an effector to inhibit bacteriophage replication.

Trait evidence (4)

DOI:10.1038/s41586-019-1605-5
cGAMP signalling is part of an antiphage defence system that is common in bacteria

Cohen et al. experimentally established a bacterial cGAS-phospholipase system as a common antiphage defense system.
DOI:10.1038/s41586-019-1605-5
Phage infection triggers the production of cGAMP

Cohen et al. support phage-triggered cyclic oligonucleotide production in an experimentally characterized cGAMP-phospholipase CBASS.
DOI:10.1038/s41564-020-0777-y
CBASS systems are composed of an oligonucleotide cyclase, which generates signalling cyclic oligonucleotides in response to phage infection

Millman et al. generalized CBASS systems as oligonucleotide-cyclase-centered antiphage signaling loci.
DOI:10.1038/s41564-020-0777-y
identified more than 5,000 CBASS systems, which have diverse architectures

Millman et al. support CBASS as a diverse recurring family across bacterial and archaeal genomes rather than a single four-gene operon.

CBASS cyclic oligonucleotides activate abortive cell death

Evidence-backed process sketch linking CBASS oligonucleotide-cyclase activation to effector activation, abortive cell death, and blocked phage replication.

NONMECHANISTIC · The graph captures the shared system-level CBASS logic of phage-triggered cyclic oligonucleotide synthesis and effector activation across multiple effector subtypes. The subtype-specific protein families carry the exact mechanistic edges and remain shifted from this first organism-level trait.

Edge evidence

CBASS oligonucleotide cyclase activation activates CBASS cyclic oligonucleotide synthesis RO:0002213
Phage sensing activates a CBASS oligonucleotide cyclase to synthesize cyclic oligonucleotide signals.
- DOI:10.1038/s41564-020-0777-y oligonucleotide cyclase, which generates signalling cyclic oligonucleotides in response to phage infection Millman et al. summarize phage-triggered oligonucleotide cyclase activation in their general CBASS model.
CBASS cyclic oligonucleotide synthesis activates CBASS effector activation RO:0002213
CBASS cyclic oligonucleotide second messengers activate cognate effector proteins.
- DOI:10.1038/s41564-020-0777-y an effector that is activated by the cyclic oligonucleotides and promotes cell death Millman et al. support effector activation as the central output of CBASS cyclic oligonucleotide signaling.
CBASS effector activation activates abortive cell death RO:0002213
CBASS effector activation induces host cell death through subtype-specific nuclease, phospholipase, or other toxic activities.
- DOI:10.1038/s41564-020-0777-y six effector subtypes that promote cell death by membrane impairment, DNA degradation or other means Millman et al. classified multiple CBASS effector subtypes that converge on host cell death.
abortive cell death mitigates phage replication METPO:2007407
CBASS-induced death of the infected host cell aborts infection before phage replication is completed.
- DOI:10.1038/s41586-019-1605-5 to cell death before completion of phage reproduction Cohen et al. experimentally tied CBASS cGAMP-phospholipase signaling to abortive cell death before the phage cycle completed.
abortive cell death confers CBASS system METPO:2007700
CBASS effector-induced abortive cell death realizes CBASS-mediated antiphage defense.
- DOI:10.1038/s41564-020-0777-y therefore preventing the spread of phages to nearby cells Millman et al. link cell death before phage replication completion to the protective output of CBASS loci.
CBASS system is a phage defense system rdfs:subClassOf
CBASS possession is a cyclic-oligonucleotide-mediated phage-defense-system trait.
- DOI:10.1038/s41564-020-0777-y a family of defence systems against bacteriophages Millman et al. place CBASS in the phage defense system family.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1038/s41586-019-1605-5

Parent traits (1)

phage defense system traitmech:000209

Synonyms (2)

cyclic-oligonucleotide-based anti-phage signalling system EXACT_SYNONYM · DOI:10.1038/s41564-020-0777-y
cyclic-oligonucleotide-based anti-phage signaling system EXACT_SYNONYM · DOI:10.1038/s41564-020-0777-y

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.

Escherichia coli TW11681 NCBITaxon:913088 DOI:10.1038/s41586-019-1605-5 Cohen et al. cloned the native E. coli TW11681 four-gene CBASS operon into E. coli MG1655 and measured P1 and coliphage resistance.

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 CBASS subtype-specific sensing and effector mechanisms before splitting cGAMP-phospholipase, cAAA-nuclease, ancillary-gene, or individual CD-NTase protein-family edges into reviewed graph groundings.

KNOWLEDGE GAP OPEN cbass-subtype-mechanism-gap · raised by codex · 2026-09-15

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

Cohen et al. resolved a phage-triggered cGAMP-phospholipase CBASS system and Millman et al. classified CBASS loci into four major types with multiple signaling molecules, effectors, and ancillary genes; exact phage sensors and subtype-specific effector families remain shifted from this first organism-level trait.

Curation history

2026-09-15T10:20:00Z · MINTED_TRAITMECH_ID · codex
Minted CBASS system as a DOI-backed GENOMICS TraitRecord under the phage defense 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_v89.