PMID:41639445

A pore-forming antiphage defence is activated by oligomeric phage proteins.

Rip1 is a small prophage-encoded protein that defends bacteria by sensing conserved oligomeric components of phage assembly

"Here we describe a 164-residue prophage-encoded protein that defends bacteria by sensing conserved oligomeric components of phage assembly."
The activating ligands are the ring-shaped portal or small terminase complexes of the infecting phage, which are required for virion maturation

"This protein, called ring interacting pore 1 (Rip1), is activated by the portal or small terminase proteins of infecting phages-oligomeric ring-shaped complexes that are essential for virion maturation."
Rip1 templates on the phage ring to assemble a membrane-disrupting pore, blocking virion assembly and killing the host cell prematurely

"Rip1 uses these phage protein ring complexes as a template to assemble into membrane-disrupting pores that inhibit phage virion assembly and cause premature death of the host cell."
Rip1 homologues are widespread in bacteria and give robust defence against diverse phages

"Rip1 homologues are widely distributed across bacteria and provide robust defence against diverse phages."
Sensing and effector activity are carried by the same single protein

"This study reveals a strategy by which a small defence protein integrates both sensing and effector activity by exploiting a conserved feature of viral assembly."
The mechanism is a prokaryotic counterpart of eukaryotic pore-forming immunity, compressed into one polypeptide

"The mechanism mirrors eukaryotic pore-forming immunity but is executed by a single protein, offering an evolutionarily streamlined solution to viral detection and defence."

PMID:18952788

Interaction between bacteriophage DMS3 and host CRISPR region inhibits group behaviors of Pseudomonas aeruginosa.

DMS3 is a temperate phage that forms lysogens of Pseudomonas aeruginosa PA14

"We observed that lysogenic infection of Pseudomonas aeruginosa PA14 with bacteriophage DMS3 inhibits biofilm formation and swarming motility, both important bacterial group behaviors."

file:9CAUD/DMS3-25/DMS3-25-bioinformatics/RESULTS.md

Sequence and genome-context analysis placing DMS3-25 in the Rip1 defence family

A0SMN5 aligns to HK446 Rip1 (PDB 9OOX chain L, the defence protein of the cited paper) over its full length at 30.8% identity with a positive score and with both C-terminal CxxC motifs conserved, while scoring negative against phage T6 small terminase (9OOX chain A, the activating ring).

"A0SMN5 aligns to Rip1 over its entire length with a positive score"
The gene is transcribed divergently from the DMS3 head-packaging operon rather than within it, the arrangement expected of a prophage accessory gene and not of a small terminase.

"an accessory gene inserted in the opposite orientation inside a structural module is the classic arrangement of a prophage moron"
The conclusion is that DMS3-25 is the defence effector rather than the phage protein that activates the defence, which is what decides the GAF qualifier.

"It is therefore the protein that executes the defence response, and the GOA qualifier"