THE RESTRICTION-ENDONUCLEASE RFLFII, ISOLATED FROM RUMINOCOCCUS-FLAVEFACIENS FD-1, RECOGNIZES THE SEQUENCE 5'-AGTACT-3', AND IS INHIBITED BY SITE-SPECIFIC ADENINE METHYLATION

Molecular studies of the rumen bacterium Ruminococcus flavefaciens are constrained by the lack of stable gene transfer systems. We report he re on the characterization of RflFII, a restriction endonuclease isola ted from R. flavefaciens FD-1. The enzyme is an isoschizomer of ScaI, and cleavage of the DNA is blunt-ended, between the internal TA dinucl eotide sequence of 5'-AGTACT-3'. Chromosomal DNA preparations were use d to demonstrate that adenine methylation of DNA within the sequence 5 '-GTAC-3' inhibits both RflFII and the restriction endonucleases RsaI and ScaI. Chromosomal DNA from R. flavefaciens FD-1 is also host modif ied to protect against cleavage by ScaI.