Directed evolution of DNA methyltransferases

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DNA methyltransferases (MTases) allow special combinations of mutagenesis and screening technologies, which will enable us to screen up to 1012 enzyme variants making this approach one of the most powerful applications of directed in vitro evolution of proteins. In order to better understand the mechanism of DNA recognition by proteins and enzymes, which underlies gene regulation in all organisms, we will try to change the DNA recognition specificity of DNA MTases in different approaches. In addition, our results will further our knowledge on the molecular mechanism of this fascinating class of enzymes. In a second groups of experiments, we will try to improve the catalytic efficiency of eukaryotic MTase domains with the aim to understand the principles of regulation of these enzymes. Erroneous methylation of the DNA is causative for many human cancers. Finally, we will try to generate an MTase variant, that is suitable for biotechnical applications and specifically methylates hemimethylated CG sites. Such enzyme could be of great use in biomedicine and biotechnology, since it would allow to develop a methylation retaining PCR - a technique that so far is not available at all. Given the special advantages of MTases for directed evolution, our results will help to define the general applicability of in vitro evolution methods as a tool to redesign complex properties of biomolecules and to estimate future prospects of this approach.