MmeI is an unusual Type II restriction enzyme that is useful for generating long sequence tags. We have cloned the MmeI restriction-modification (R-M) system and found it to consist of a single protein having both endonuclease and DNA methyltransferase activities. The protein comprises an amino-terminal endonuclease domain, a central DNA methyltransferase domain and C-terminal DNA recognition d...

Complete genome sequences of two closely related cellular organisms became available for the first time for two Helicobacter pylori strains [1,4]. Their comparison at single base pair level suggested presence of a novel mechanism for gene mobility — insertion with long target duplication [3]. It is formally similar to transposon insertion, but the duplication is much longer (often in the range ...

The LlaI restriction and modification (R/M) system is encoded on pTR2030, a 46.2-kb conjugative plasmid from Lactococcus lactis. The llaI methylase gene, sequenced previously, encodes a functional type IIS methylase and is located approximately 5 kb upstream from the abiA gene, encoding abortive phage resistance. In this study, the sequence of the region between llaIM and abiA was determined an...