title: ATP utilization by rep protein in the catalytic separation of DNA strands at a replicating fork.
abstract: Hydrolysis of ATP by rep protein proceeds in the presence of a single-stranded region of DNA 4 residues long, but the true effector for rep ATPase appears to be a replicating fork rather than a random coil. At or near a fork in duplex DNA, rep ATPase action is different from what it is on DNA lacking secondary structure (single-stranded): (i) Km for ATP is lower, (ii) specificity is for ATP and dATP with no action on other nucleoside triphosphates, (iii) sensitivity to certain ATP analogs is reduced, (iv) presence of a DNA-nicking enzyme (e.g. cistron A protein induced by phiX174) is required, and (v) Escherichia coli DNA binding protein facilitates rather than inhibits. During the separation of strands accompanying replication, 2 molecules of nucleoside triphosphate (ATP or dATP) are hydrolyzed for every nucleotide polymerized. Utilization of ATP by rep protein may provide energy for catalytic strand separation at a fork in advance of replication.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D004247:DNA; D004261:DNA Replication; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D011089:Polydeoxyribonucleotides
chemical_list: D011089:Polydeoxyribonucleotides; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D008274:Magnesium