This project takes advantage of a DNA sequencing technology newly developed by Pacific Biosciences called SMRT sequencing. In addition to providing the DNA base sequence, this approach also allows the detection of modified bases. DNA methyltransferases have traditionally been rather difficult to characterize and as a result, we do not currently know the accurate DNA recognition specificity of any DNA methyltransferases. In the case of those that form part of restriction-modification systems, it has always been assumed that they will have the same recognition specificity as the restriction enzyme. However, in some systems preliminary results indicated that this might not be so, and we now in a position to test that explicitly. A knowledge of the specificity will be key on many fronts. Firstly, in some cases it will allow these methyltransferases to become valuable commercial reagents. Secondly, we expect to discover novel DNA methyltransferases with properties that would make them suitable for specific applications. One such enzyme discovered very recently, is M.EcoGI, which appears to recognize all A residues in a sequence and convert them at very high efficiency to N6- methyladenine. The results of this project will also greatly enhance the value of the cloned restriction-modification systems that we have at New England Biolabs and will also help considerably in the functional annotation of newly determined DNA sequences. It is an ideal blend of academic and commercial research and therefore is especially suited for New England Biolabs.
This project will characterize a large number of DNA methyltransferase genes in terms of their DNA recognition sequences as well as the specific base modified. These methyltransferases, once characterized, can serve as useful research reagents and their characterization will also help to improve genome annotation, which can be especially important for bacterial pathogens.
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