Single strand annealing and ATP-independent strand exchange activities of yeast and human DNA2: possible role in Okazaki fragment maturation.
The Dna2 protein is a multifunctional enzyme with 5'-3' DNA helicase, DNA-dependent ATPase, 3' exo/endonuclease, and 5' exo/endonuclease. The enzyme is highly specific for structures containing single-stranded flaps adjacent to duplex regions. We report here two novel activities of both the yeast and human Dna2 helicase/nuclease protein: single strand annealing and ATP-independent strand exchange on short duplexes. These activities are independent of ATPase/helicase and nuclease activities in that mutations eliminating either nuclease or ATPase/helicase do not inhibit strand annealing or strand exchange. ATP inhibits strand exchange. A model rationalizing the multiple catalytic functions of Dna2 and leading to its coordination with other enzymes in processing single-stranded flaps during DNA replication and repair is presented.
Masuda-Sasa
Taro
T
Braun Laboratories, California Institute of Technology, Pasadena, CA 91125, USA.
Polaczek
Piotr
P
Campbell
Judith L
JL
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D017931:DNA Primers; D006801:Humans; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
D017931:DNA Primers; C022262:Okazaki fragments; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; C410222:DNA2 protein, S cerevisiae; C509908:DNA2 protein, human