ATPase activity of the type IC restriction-modification system EcoR124II.
We have investigated the ATPase activity of the type IC restriction-modification (R-M) system EcoR124II. As with all type I R-M systems EcoR 124II requires ATP hydrolysis to cut DNA. We determined the KM for ATP to be 10(-5) to 10(-4) M. By measuring ATP hydrolysis under different conditions and by simultaneously monitoring DNA restriction, methylation and ATP hydrolysis we propose that the order of events during restriction is: (1) binding of EcoR124II to a non-methylated recognition sequence, (2) start of DNA-dependent ATP hydrolysis which continues even after restriction is complete, (3) restriction of DNA, (4) methylation of the product. Non-cleavable DNA substrates, such as recognition site containing oligonucleotides, also support ATP hydrolysis. Methylation can also occur prior to ATP hydrolysis and prevent DNA degradation.
Dreier
J
J
Department of Microbiology Biozentrum, Basel University, Switzerland.
Bickle
T A
TA
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D004996:Ethidium / Q000494:pharmacology; D007700:Kinetics; D008745:Methylation; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000378:metabolism
D009838:Oligodeoxyribonucleotides; D000255:Adenosine Triphosphate; D004247:DNA; C072994:EcoR124 modification methylase type I; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); D003850:Deoxyribonuclease I; D000251:Adenosine Triphosphatases; D004996:Ethidium