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AbiQ, an abortive infection mechanism from Lactococcus lactis
1Department of Biochemistry and Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec, G1K 7P4 Canada.
Applied and Environmental Microbiology
|December 3, 1998
Summary
Lactococcus lactis W-37 plasmid pSRQ900 confers phage resistance by encoding an abortive infection mechanism, AbiQ. This mechanism prevents phage DNA maturation, offering protection against specific phage types.
Area of Science:
- Microbiology
- Bacteriology
- Molecular Biology
Background:
- Lactococcus lactis is susceptible to phage infections, impacting dairy production.
- Phage resistance mechanisms are crucial for industrial applications of L. lactis.
Purpose of the Study:
- To identify the genetic basis of phage resistance in Lactococcus lactis W-37.
- To characterize the phage resistance mechanism encoded by plasmid pSRQ900.
Main Methods:
- Plasmid isolation and electroporation into a plasmid-free host.
- Phage resistance assays (efficiency of plaquing).
- Genetic analysis including sequencing and site-directed mutagenesis.
- DNA replication and protein production assays.
Main Results:
- Plasmid pSRQ900 from L. lactis W-37 conferred high resistance to c2- and 936-like phages.
- The resistance mechanism, an abortive infection, was localized to a 2.2-kb fragment containing the abiQ gene.
- AbiQ is a novel gene encoding a putative cytosolic protein that prevents phage DNA maturation but not replication or capsid protein synthesis.
Conclusions:
- Plasmid pSRQ900 and its abiQ gene provide a novel abortive infection mechanism against specific L. lactis phages.
- AbiQ represents a new class of phage resistance proteins.
- Understanding AbiQ function can aid in developing phage-resistant L. lactis strains for industrial use.