SegI restriction endonuclease from Sphingobium erigeronicola 46 recognizes the octanucleotide DNA sequence 5′-RTGC↓GCAY-3′ and is an isoschizomer of FspAI
We identified a bacterial strain, Sphingobium erigeronicola 46, that produces a novel rare-cutting restriction endonuclease, designated SegI. The enzyme recognizes the degenerate palindromic octanucleotide DNA sequence 5′-RTGC↓GCAY-3′ and cleaves both DNA strands in the center of the recognition site, as indicated by the arrow, generating blunt ends. SegI is therefore an isoschizomer of the previously described restriction endonuclease FspAI . The recognition sequence was determined by analyzing the restriction patterns generated by SegI digestion of bacteriophage λ DNA (predigested with BssT1I), bacteriophage T7 DNA, and plasmid pBR322 DNA, followed by electrophoresis in a 0.8% agarose gel.
The producing strain was identified based on its morphological characteristics and sequence analysis of a 16S rRNA gene fragment. A SegI restriction endonuclease preparation with an activity of 5,000 U/mL was obtained through a three-step chromatographic purification procedure. The precise…