Isolation, cloning and characterisation of the abiI gene from Lactococcus lactis subsp. lactis M138 encoding abortive phage infection

Abstract

Plasmid pND852 (56 kb) encodes nisin resistance and was isolated from Lactococcus lactis ssp lactis (L. lactis) M138 by conjugation to L. lactis LM0230. It conferred strong resistance to the isometric-headed phage φ712 and partial resistance to the prolate-headed phage φc2. A 2.6 kb HpaII fragment encoding phage resistance was cloned into the streptococcal/Bacillus hybrid vector pGB301 to generate pND817. The mechanism of phage resistance encoded by pND817 involved abortive infection and this was illustrated by a reduction in burst size from 166 to 6 at 30°C and from 160 to 90 at 37°C. Partial resistance was therefore retained at 37°C. DNA sequencing revealed that the abortive infection was encoded by a single open reading frame (ORF), designated abiI, encoding a 332 amino acid protein. Neither abiI nor the predicted product showed significant homology to any existing sequence in the GenBank database. Frame shift mutation at the unique EcoRI site within the ORF resulted in loss of the Abi + phenotype, confirming that the ORF is responsible for the encoded phage resistance.

Microbiological and molecular impacts of AbiK on the lytic cycle of Lactococcus lactis phages of the 936 and P335 species

“…mond et al, 1998). Three other Abi genes were also sequenced, namely, AbiI (Su et al, 1997), AbiO (Pre! vots & Ritzenthaler, 1998) and AbiP (GenGank accession no.…”

Lactococcus lactis phage operon coding for an endonuclease homologous to RuvC

“…Lactococcus lactis species are industrially important microorganisms that are under strong selective pressure from the bacteriophages present in the dairy environment. These organisms were found to possess various Abi mechanisms, and the genes involved in 13 of them have been cloned and sequenced (Hill, 1993;Daly et al, 1996;Prevots et al, 1996;Deng et al, 1997;Emond et al, 1997;Su et al, 1997;Y.-M. Deng and N. W. Dunn, unpublished). However, the primary effects on phage development are presently known only for AbiA, AbiB and AbiD1 (Hill et al, 1991;Anba et al, 1995;Parreira et al, 1996;Dinsmore and Klaenhammer, 1997).…”

Development of food-grade cloning and expression vectors for Lactococcus lactis

“…Phage propagation, titration and assay for efficiency of plaquing (EOP) were as described previously (Su et al. 1997).…”

“…Infection of L. lactis by bacteriophages still remains as a major problem in the dairy industry. We have previously cloned a phage abortive infection gene ( abiI ) from L. lactics M138 (Su et al. 1997).…”