'Pseudo' domains in phage-encoded DNA methyltransferases |
| |
Authors: | C Lange A Jugel J Walter M Noyer-Weidner T A Trautner |
| |
Institution: | Max-Planck-Institut für molekulare Genetik, Berlin, Germany. |
| |
Abstract: | 5-Cytosine-DNA-methyltransferases, which are found in many organisms ranging from bacteriophages to mammals, transfer a methyl group from S-adenosylmethionine to the carbon-5 of a cytosine residue in specific DNA target sequences. Some phage-encoded methyltransferases methylate more than one sequence: these enzymes contain several independent target-recognizing domains each responsible for recognizing a different site. The amino-acid sequences of these multispecific methyltransferases reveal that some enzymes in addition carry domains that do not contribute to the enzymes' methylation potential, but strongly resemble previously identified target-recognizing domains. Here we show that introducing defined amino-acid alterations into these inactive domains endows these enzymes with additional methylation specificities. Gel retardation analysis demonstrates that these novel methylation specificities correlate with the acquisition of additional DNA-binding potential of the proteins. |
| |
Keywords: | |
|
|