Phenotypic and genetic characterization of the bacteriophage abortive infection mechanism AbiK from Lactococcus lactis
| Autor: | Barbara J. Holler, Jeffrey K. Kondo, Éric Émond, Peter A. Vandenbergh, Sylvain Moineau, Isabelle Boucher, Ebenezer R. Vedamuthu |
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| Rok vydání: | 1997 |
| Předmět: |
viruses
Molecular Sequence Data EcoRI Molecular cloning Applied Microbiology and Biotechnology Bacteriophage chemistry.chemical_compound Open Reading Frames Plasmid Bacterial Proteins Bacteriophages Amino Acid Sequence Cloning Molecular Genetics Ecology biology Base Sequence Lactococcus lactis Nucleic acid sequence DNA replication biology.organism_classification Molecular biology chemistry DNA Viral biology.protein DNA Food Science Biotechnology Plasmids Research Article |
| Zdroj: | Applied and environmental microbiology. 63(4) |
| ISSN: | 0099-2240 |
| Popis: | The natural plasmid pSRQ800 isolated from Lactococcus lactis subsp. lactis W1 conferred strong phage resistance against small isometric phages of the 936 and P335 species when introduced into phage-sensitive L. lactis strains. It had very limited effect on prolate phages of the c2 species. The phage resistance mechanism encoded on pSRQ800 is a temperature-sensitive abortive infection system (Abi). Plasmid pSRQ800 was mapped, and the Abi genetic determinant was localized on a 4.5-kb EcoRI fragment. Cloning and sequencing of the 4.5-kb fragment allowed the identification of two large open reading frames. Deletion mutants showed that only orf1 was needed to produce the Abi phenotype. orf1 (renamed abiK) coded for a predicted protein of 599 amino acids (AbiK) with an estimated molecular size of 71.4 kDa and a pI of 7.98. DNA and protein sequence alignment programs found no significant homology with databases. However, a database query based on amino acid composition suggested that AbiK might be in the same protein family as AbiA. No phage DNA replication nor phage structural protein production was detected in infected AbiK+ L. lactis cells. This system is believed to act at or prior to phage DNA replication. WHen cloned into a high-copy vector, AbiK efficiency increased 100-fold. AbiK provides another powerful tool that can be useful in controlling phages during lactococcal fermentations. |
| Databáze: | OpenAIRE |
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