'Pseudo' domains in phage-encoded DNA methyltransferases.
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.
Lange
C
C
Max-Planck-Institut für molekulare Genetik, Berlin, Germany.
Jugel
A
A
Walter
J
J
Noyer-Weidner
M
M
Trautner
T A
TA
D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000201:enzymology; D001665:Binding Sites; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D015257:DNA-Cytosine Methylases / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D004268:DNA-Binding Proteins; D015257:DNA-Cytosine Methylases; D004248:DNA (Cytosine-5-)-Methyltransferases