Phenotypic and genetic characterization of the bacteriophage abortive infection mechanism AbiK from Lactococcus lactis.
AUTOR(ES)
Emond, E
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=168421Documentos Relacionados
- AbiQ, an Abortive Infection Mechanism from Lactococcus lactis
- Characterization of the Two-Component Abortive Phage Infection Mechanism AbiT from Lactococcus lactis
- Cloning and characterization of the abortive infection genetic determinant abiD isolated from pBF61 of Lactococcus lactis subsp. lactis KR5.
- Phage operon involved in sensitivity to the Lactococcus lactis abortive infection mechanism AbiD1.
- Molecular Characterization of a New Abortive Infection System (AbiU) from Lactococcus lactis LL51-1