Dataset Information

Involvement of the LlaKR2I methylase in expression of the AbiR bacteriophage defense system in Lactococcus lactis subsp. lactis biovar diacetylactis KR2.

ABSTRACT: The native lactococcal plasmid, pKR223, from Lactococcus lactis subsp. lactis biovar diacetylactis KR2 encodes two distinct bacteriophage-resistant mechanisms, the LlaKR2I restriction and modification (R/M) system and the abortive infection (Abi) mechanism, AbiR, that impedes bacteriophage DNA replication. This study completed the characterization of AbiR, revealing that it is the first Abi system to be encoded by three genes, abiRa, abiRb, and abiRc, arranged in an operon and that it requires the methylase gene from the LlaKR2I R/M system. An analysis of deletion and insertion clones demonstrated that the AbiR operon was toxic in L. lactis without the presence of the LlaKR2I methylase, which is required to protect L. lactis from AbiR toxicity. The novelty of the AbiR system resides in its original gene organization and the unusual protective role of the LlaKR2I methylase. Interestingly, the AbiR genetic determinants are flanked by two IS982 elements generating a likely transposable AbiR composite. This observation not only substantiated the novel function of the LlaKR2I methylase in the AbiR system but also illustrated the evolution of the LlaKR2I methylase toward a new and separate cellular function. This unique structure of both the LlaKR2I R/M system and the AbiR system may have contributed to the evolution of the LlaKR2I methylase toward a novel role comparable to that of the cell cycle-regulated methylases that include Dam and CcrM methylases. This new role for the LlaKR2I methylase offers a unique snapshot into the evolution of the cell cycle-regulated methylases from an existing R/M system.

SUBMITTER: Yang JM

PROVIDER: S-EPMC1426540 | biostudies-literature | 2006 Mar

REPOSITORIES: biostudies-literature

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Involvement of the LlaKR2I methylase in expression of the AbiR bacteriophage defense system in Lactococcus lactis subsp. lactis biovar diacetylactis KR2.

Yang Julie M JM Deurraza Patricio J PJ Matvienko Nadya N O'Sullivan Daniel J DJ

Journal of bacteriology 20060301 5

The native lactococcal plasmid, pKR223, from Lactococcus lactis subsp. lactis biovar diacetylactis KR2 encodes two distinct bacteriophage-resistant mechanisms, the LlaKR2I restriction and modification (R/M) system and the abortive infection (Abi) mechanism, AbiR, that impedes bacteriophage DNA replication. This study completed the characterization of AbiR, revealing that it is the first Abi system to be encoded by three genes, abiRa, abiRb, and abiRc, arranged in an operon and that it requires t ...[more]

PMID: 16484203

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Project description:BACKGROUND:Important industrial traits have been linked to plasmids in Lactococcus lactis. RESULTS:The dairy isolate L. lactis subsp. lactis biovar diacetylactis FM03P was sequenced revealing the biggest plasmidome of all completely sequenced and published L. lactis strains up till now. The 12 plasmids that were identified are: pLd1 (8277 bp), pLd2 (15,218 bp), pLd3 (4242 bp), pLd4 (12,005 bp), pLd5 (7521 bp), pLd6 (3363 bp), pLd7 (30,274 bp), pLd8 (47,015 bp), pLd9 (15,313 bp), pLd10 (39,563 bp), pLd11 (9833 bp) and pLd12 (3321 bp). Structural analysis of the repB promoters and the RepB proteins showed that eleven of the plasmids replicate via the theta-type mechanism, while only plasmid pLd3 replicates via a rolling-circle replication mechanism. Plasmids pLd2, pLd7 and pLd10 contain a highly similar operon involved in mobilisation of the plasmids. Examination of the twelve plasmids of L. lactis FM03P showed that 10 of the plasmids carry putative genes known to be important for growth and survival in the dairy environment. These genes encode technological functions such as lactose utilisation (lacR-lacABCDFEGX), citrate uptake (citQRP), peptide degradation (pepO and pepE) and oligopeptide uptake (oppDFBCA), uptake of magnesium and manganese (2 mntH, corA), exopolysaccharides production (eps operon), bacteriophage resistance (1 hsdM, 1 hsdR and 7 different hsdS genes of a type I restriction-modification system, an operon of three genes encoding a putative type II restriction-modification system and an abortive infection gene) and stress resistance (2 uspA, cspC and cadCA). Acquisition of these plasmids most likely facilitated the adaptation of the recipient strain to the dairy environment. Some plasmids were already lost during a single propagation step signifying their instability in the absence of a selective pressure. CONCLUSIONS:Lactococcus lactis FM03P carries 12 plasmids important for its adaptation to the dairy environment. Some of the plasmids were easily lost demonstrating that propagation outside the dairy environment should be minimised when studying dairy isolates of L. lactis.

Dataset Information

Involvement of the LlaKR2I methylase in expression of the AbiR bacteriophage defense system in Lactococcus lactis subsp. lactis biovar diacetylactis KR2.

Publications

Involvement of the LlaKR2I methylase in expression of the AbiR bacteriophage defense system in Lactococcus lactis subsp. lactis biovar diacetylactis KR2.

Similar Datasets

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