DNA methylation in mycobacteria: absence of methylation at GATC (Dam) and CCA/TGG (Dcm) sequences.
The presence of 6-methyladenine and 5-methylcytosine at Dam (GATC) and Dcm (CCA/TGG) sites in DNA of mycobacterial species was investigated using isoschizomer restriction enzymes. In all species examined, Dam and Dcm recognition sequences were not methylated indicating the absence of these methyltransferases. On the other hand, high performance liquid chromatographic analysis of genomic DNA from Mycobacterium smegmatis and Mycobacterium tuberculosis showed significant levels of 6-methyladenine and 5-methylcytosine suggesting the presence of DNA methyltransferases other than Dam and Dcm. Occurrence of methylation was also established by a sensitive genetic assay.
Centre for Genetic Engineering, Indian Institute of Science, Bangalore, India.
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Hemavathy
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Nagaraja
D044503:5-Methylcytosine; D000241:Adenosine / Q000031:analogs & derivatives* / Q000032:analysis; D001483:Base Sequence; D003596:Cytosine / Q000031:analogs & derivatives* / Q000032:analysis; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000032:analysis*; D004269:DNA, Bacterial / Q000378:metabolism*; D015257:DNA-Cytosine Methylases / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000145:classification / Q000201:enzymology*; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000472:pathogenicity; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000032:analysis* / Q000378:metabolism*; D013045:Species Specificity; D013379:Substrate Specificity; D014774:Virulence
D004269:DNA, Bacterial; D044503:5-Methylcytosine; D003596:Cytosine; C010223:N-methyladenosine; D015257:DNA-Cytosine Methylases; D004248:DNA (Cytosine-5-)-Methyltransferases; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C020102:endodeoxyribonuclease DpnI; C046545:CCWGG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; C024405:GATC-specific type II deoxyribonucleases; D000241:Adenosine