INTERACTIONS BETWEEN THE METHYLATION SITES OF THE ESCHERICHIA-COLI ASPARTATE RECEPTOR-MEDIATED BY THE METHYLTRANSFERASE

Mutations made at and near the methylation sites of the Escherichia co li aspartate receptor were found to affect the methylation rates of th e remaining methylation sites. The results supported a model in which the methyltransferase enzyme contacts a residue seven amino acids to t he C terminus of a site being methylated. The presence of a negatively charged residue at that position inhibits methylation, whereas a neut ral residue has no effect. Methylation sites in the wild type receptor may also influence the methylation of other sites which are 7 residue s away through a physical contact with the methyltransferase.