title: Restriction-modification systems in Lactococcus lactis.
abstract: Several restriction-modification (R-M) systems have been identified in Lactococcus lactis. Most of the systems have been plasmid encoded and function as phage-resistance mechanisms. At least five different type-II R-M systems, LlaAI, LlaBI, LlaCI, LlaDI and LlaEI, were identified in isolates from a mixed Cheddar starter culture. LlaAI and LlaBI recognized the DNA sequences 5'- decreases GATC-3' and 5'-C decreases TRYAG-3', respectively. The genes coding for the LlaAI and LlaBI R-M systems have been cloned and sequenced. The LlaAI R-M system had two genes coding for methyltransferases (MTases) and one gene coding for a restriction endonuclease (ENase). The MTases showed high homology to the MTases from DpnII. The LlaBI R-M system had one gene coding for a MTase and one gene coding for an ENase.
authors.affiliation: Department of Dairy and Food Science, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Nyengaard
authors.forename: F K
authors.initials: FK
authors.lastname: Vogensen
authors.forename: J
authors.initials: J
authors.lastname: Josephsen
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D005798:Genes, Bacterial; D007700:Kinetics; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics; D010957:Plasmids; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011994:Recombinant Proteins; D004262:DNA Restriction Enzymes; C085497:endodeoxyribonuclease SfcI; D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases