In vivo and in vitro studies of Mgs1 suggest a link between genome instability and Okazaki fragment processing.
The non-essential MGS1 gene of Saccharomyces cerevisiae is highly conserved in eukaryotes and encodes an enzyme containing both DNA-dependent ATPase and DNA annealing activities. MGS1 appears to function in post-replicational repair processes that contribute to genome stability. In this study, we identified MGS1 as a multicopy suppressor of the temperature-sensitive dna2Delta405N mutation, a DNA2 allele lacking the N-terminal 405 amino acid residues. Mgs1 stimulates the structure-specific nuclease activity of Rad27 (yeast Fen1 or yFen1) in an ATP-dependent manner. ATP binding but not hydrolysis was sufficient for the stimulatory effect of Mgs1, since non-hydrolyzable ATP analogs are as effective as ATP. Suppression of the temperature-sensitive growth defect of dna2Delta405N required the presence of a functional copy of RAD27, indicating that Mgs1 suppressed the dna2Delta405N mutation by increasing the activity of yFen1 (Rad27) in vivo. Our results provide in vivo and in vitro evidence that Mgs1 is involved in Okazaki fragment processing by modulating Fen1 activity. The data presented raise the possibility that the absence of MGS1 may impair the processing of Okazaki fragments, leading to genomic instability.
Kim
Jeong-Hoon
JH
Department of Biological Sciences, National Creative Research Initiative Center for Cell Cycle Control, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea.
Kang
Young-Hoon
YH
Kang
Hyo-Jin
HJ
Kim
Do-Hyung
DH
Ryu
Gi-Hyuck
GH
Kang
Min-Jung
MJ
Seo
Yeon-Soo
YS
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D045585:Flap Endonucleases / Q000378:metabolism; D016153:Genes, Suppressor; D042822:Genomic Instability; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017384:Sequence Deletion
C022262:Okazaki fragments; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D045585:Flap Endonucleases; D000251:Adenosine Triphosphatases; C506739:MGS1 protein, S cerevisiae; D004265:DNA Helicases; C410222:DNA2 protein, S cerevisiae