Enrique González and Claudio Vásquez Laboratorio de Biología Molecular, Departamento de Ciencias Biológicas, Universidad de Talca, Casilla 747, Talca, Chile.The nucleotide (nt) sequence of a 2.7-kb HindIII-EcoRI DNA fragment encoding the bstVIR and bstVIM genes has been determined. The sequence predicts a restriction endonuclease of 224 amino acids (aa), M(r) 25 104, and a methyl-transferase of 561 aa, M(r) 65 702. Both genes are aligned in the same orientation and are separated by a 102-nt intergenic region. No homology was found between R.BstVI and M.BstVI when their deduced aa sequences were compared. Significant similarity at the aa level was found, however, when both enzymes were compared to their equivalents in the paeR7IRM system of Pseudomonas aeruginosa PAO303.