Cloning and analysis of a novel human putative DNA methyltransferase

DNA methylation is intricately involved in a variety of cellular processes, such as differentiation, cell cycle progression, X-chromosome inactivation and genomic imprinting. However, little is known about how specific DNA methylation patterns are established and maintained. Previously one mammalian DNA methyltransferase has been described, but there has been considerable speculation about the presence of a second activity capable of methylation. Here we report the identification and characterization of a novel human putative DNA methyltransferase. Using a bioinformatics screen we have identified several expressed sequence tags which show high sequence similarity to the Schizosaccharomyces pombe gene pmt1+. The cDNA for PuMet (for putative DNA methyltransferase) was cloned and the predicted amino acid sequence deduced. The gene is ubiquitously expressed, albeit at low levels. Like several other DNA methyltransferases, the bacterially overexpressed protein is not active in methylation assays.