Human replication factor C stimulates flap endonuclease 1.
Flap endonuclease 1 (FEN1) is the enzyme responsible for specifically removing the flap structure produced during DNA replication, repair, and recombination. Here we report that the human replication factor C (RFC) complex stimulates the nuclease activity of human FEN1 in an ATP-independent manner. Although proliferating cell nuclear antigen is also known to stimulate FEN1, less RFC was required for comparable FEN1 stimulation. Kinetic analyses indicate that the mechanism by which RFC stimulates FEN1 is distinct from that by proliferating cell nuclear antigen. Heat-denatured RFC or its subunit retained, fully or partially, the ability to stimulate FEN1. Via systematic deletion analyses, we have defined three specific regions of RFC4 capable of stimulating FEN1. The region of RFC4 with the highest activity spans amino acids 170-194 and contains RFC box VII. Four amino acid residues (i.e. Tyr-182, Glu-188, Pro-189, and Ser-192) are especially important for FEN1 stimulatory activity. Thus, RFC, via several stimulatory motifs per molecule, potently activates FEN1. This function makes RFC a critical partner with FEN1 for the processing of eukaryotic Okazaki fragments.
Cho
Il-Taeg
IT
Center for DNA Replication and Genome Instability, Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea.
Kim
Do-Hyung
DH
Kang
Young-Hoon
YH
Lee
Chul-Hwan
CH
Amangyelid
Tamir
T
Nguyen
Tuan Anh
TA
Hurwitz
Jerard
J
Seo
Yeon-Soo
YS
D000595:Amino Acid Sequence; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D051818:Replication Protein C / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
D004277:DNA, Single-Stranded; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D045585:Flap Endonucleases; C468317:FEN1 protein, human; C468323:RAD27 protein, S cerevisiae; D051818:Replication Protein C