Molecular characterization of the DNA methyltransferase M1.NcuI from Neisseria cuniculi ATCC 14688.

The methyltransferase M1.NcuI is a member of the restriction-modification system in Neisseria cuniculi ATCC14688 and recognizes the asymmetric pentanucleotide sequence 5'-GAAGA-3'/3'-CTTCT-5'. We purified M1.

Isolation and characterization of type IIS restriction endonuclease from Neisseria cuniculi ATCC 14688.

Neisseria cuniculi produces the restriction enzyme NcuI which is an isoschizomer of MboII. We have demonstrated that NcuI recognizes a pentanucleotide sequence (5'-GAAGA-3'/3'-CTTCT-5'), and cleaves the DNA 8 and 7 nucleotides downstream from the recognition site leaving a single 3'-protruding nucleotide. We have purified this enzyme to electrophoretic homogeneity using a four-step chromatographic procedure.

Identification, characterization and purification of the lantibiotic staphylococcin T, a natural gallidermin variant.

Staphylococcin T (StT), an antibacterial agent produced by a Staphylococcus cohnii T strain, was purified to homogeneity by ammonium sulphate precipitation, gel filtration, cation exchange and fast performance liquid chromatography (FPLC). The final yield was about 20%, and over a 1000-fold increase in the specific activity was obtained. Mass determination (2166 Da), amino acid sequencing (Ile-Ala-Xaa-Lys-Phe-Leu-Xaa-Xaa-Pro-Gly-Xaa-Ala-Lys-block) and DNA sequencing demonstrated that StT is identical to gallidermin, a lanthionine-containing antimicrobial peptide.