title: Escherichia coli RecQ protein is a DNA helicase.
abstract: The Escherichia coli recQ gene, a member of the RecF recombination gene family, was set in an overexpression plasmid, and its product was purified to near-homogeneity. The purified RecQ protein exhibited a DNA-dependent ATPase and a helicase activity. Without DNA, no ATPase activity was detected. The capacity as ATPase cofactor varied with the type of DNA in the following order: circular single strand greater than linear single strand much greater than circular or linear duplex. As a helicase, RecQ protein displaced an annealed 71-base or 143-base single-stranded fragment from circular or linear phage M13 DNA, and the direction of unwinding seemed to be 3'----5' with respect to the DNA single strand to which the enzyme supposedly bound. Furthermore, the protein could unwind 143-base-pair blunt-ended duplex DNA at a higher enzyme concentration. It is concluded that RecQ protein is a previously unreported helicase, which might possibly serve to generate single-stranded tails for a strand transfer reaction in the process of recombination.
authors.affiliation: Department of Microbiology, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Umezu
authors.forename: K
authors.initials: K
authors.lastname: Nakayama
authors.forename: H
authors.initials: H
authors.lastname: Nakayama
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D004265:DNA Helicases / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D007700:Kinetics; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010957:Plasmids; D053484:RecQ Helicases; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D015183:Restriction Mapping
chemical_list: D015345:Oligonucleotide Probes; D011993:Recombinant Fusion Proteins; D000251:Adenosine Triphosphatases; C506724:RecQ protein, E coli; D004265:DNA Helicases; D053484:RecQ Helicases