title: Combinational variation of restriction modification specificities in Lactococcus lactis.
abstract: Three genes coding for a type I R-M system related to the class C enzymes have been identified on the chromosome of Lactococcus lactis strain IL1403. In addition, plasmids were found that encode only the HsdS subunit that directs R-M specificity. The presence of these plasmids in IL1403 conferred a new R-M phenotype on the host, indicating that the plasmid-encoded HsdS is able to interact with the chromosomally encoded HsdR and HsdM subunits. Such combinational variation of type I R-M systems may facilitate the evolution of their specificity and thus reinforce bacterial resistance against invasive foreign unmethylated DNA.
authors.affiliation: INRA, Laboratoire de Génétique Microbienne, Jouy-en-Josas, France.
authors.forename: C
authors.initials: C
authors.lastname: Schouler
authors.forename: M
authors.initials: M
authors.lastname: Gautier
authors.forename: S D
authors.initials: SD
authors.lastname: Ehrlich
authors.forename: M C
authors.initials: MC
authors.lastname: Chopin
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001435:Bacteriophages / Q000235:genetics; D003001:Cloning, Molecular; D015280:DNA Restriction-Modification Enzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005784:Gene Amplification; D005798:Genes, Bacterial; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D015280:DNA Restriction-Modification Enzymes; C113046:HSDS protein, Bacteria