Cloning, sequence analysis and heterologous expression of the DNA adenine-(N-6) methyltransferase from the human pathogen Actinobacillus actinomycetemcomitans

We cloned and sequenced the DNA adenine-N-6 methyltransferase gene of the h uman pathogen Actinobacillus actinomycetemcomitans (M.AacDAM). Restriction digestion shows that the enzyme methylates adenine in the sequence GATC. Ex pression of the enzyme in a DAM(-) background shows in vivo activity. A PSI -BLAST search revealed that M.AacDAM is most related to M.HindIV. M.EcoDAM, M.StyDAM. and M.Small. The ClustalW alignment shows highly conserved regio ns in the enzyme characteristic for type a MTases. Phylogenetic tree analys is shows a cluster of enzymes recognizing the sequence GATC, within a branc h of orphan MTases harboring M.AacDAM, The cloning and sequencing of this f irst methyltransferase gene described for A. actinomycetemcomitans open the path for studies on the potential regulatory impact of DNA methylation on gene regulation and virulence in this organism. (C) 2001 Federation of Euro pean Microbiological Societies. Published by Elsevier Science B.V. All righ ts reserved.