Abortive infection (Abi) systems, also called phage exclusion, block phage multiplication and cause premature bacterial cell death upon phage infection. This decreases the number of progeny particles and limits their spread to other cells allowing the bacterial population to survive. Twenty Abi systems have been isolated in Lactococcus lactis, a bacterium used in cheese-making fermentation processes, where phage attacks are of economical importance. Recent insights in their expression and mode of action indicate that, behind diverse phenotypic and molecular effects, lactococcal Abis share common traits with the well-studied Escherichia coli systems Lit and Prr. Abis are widespread in bacteria, and recent analysis indicates that Abis might have additional roles other than conferring phage resistance.
A 16-kb plasmid (pND859) was identified from Lactococcus lactis biovar. diacetylactis UK12922 which encodes phage resistance to the small isometric phage 712 when tested in L. lactis LM0230. The gene encoding phage abortive infection, designated abi-859, was localized on a 1.2-kb region which consists of an open reading frame (ORF) of 846 bp preceded by a potential ribosome-binding site and a putative promoter region. A helix-turn-helix region typical of DNA-binding motifs was identified near the N-terminal of the abi-859 product, suggesting a possible interaction with the phage DNA.
Sensor:Unknown
Activator:Unknown
Effector:Unknown
PFAM:PF13175, PF13304, PF13707
contributors:
-Ernest Mordret
relevantAbstracts:
-doi:10.1111/j.1574-6968.1997.tb10185.x
-doi:10.1016/j.mib.2005.06.006
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# AbiL
## Description
AbiL was discovered in Lactococcus lactis. A plasmid containing the defense system was found to prevent infection by phage 712 through an abortive infection system
## Molecular mechanism
Abortive infection. the PF13707 domain includes the RloB protein that is found within a bacterial restriction modification operon. This family includes the AbiLii protein that is found as part of a plasmid encoded phage abortive infection mechanism. Deletion within abiLii abolished the phage resistance. The family includes some proteins annotated as CRISPR Csm2 proteins.
## Example of genomic structure
The AbiL system is composed of 2 proteins: AbiLii2 and, AbiLi2.
