STATISTICAL SIGNIFICANCE OF AMINO-ACID-SE QUENCE SIMILARITY IN TYPE-II DNA METHYLTRANSFERASES

The statistical significance of amino acid sequence similarities previ ously observed in type II DNA methyltransferases has been investigated . It is shown: (1) that the intramolecular similarities observed among various type II Mtases are not statistically significant and thus can not be used to support a gene duplication model; (2) that the intermo lecular similarities observed in a peptide in various type II adenine methylases are statistically confirmed; (3) that the similarities obse rved between MutH and these proteins for this peptide are not statisti cally significant and therefore cannot be used to propose a functional role in DNA recognition for this peptide.