Mechanism of Werner DNA helicase: POT1 and RPA stimulates WRN to unwind beyond gaps in the translocating strand.
WRN belongs to the RecQ family of DNA helicases and it plays a role in recombination, replication, telomere maintenance and long-patch base excision repair. Here, we demonstrate that WRN efficiently unwinds DNA substrates containing a 1-nucleotide gap in the translocating DNA strand, but when the gap size is increased to 3-nucleotides unwinding activity significantly declines. In contrast, E. coli UvrD (3'-->5' helicase), which recognizes nicks in DNA to initiate unwinding, does not unwind past a 1-nucleotide gap. This unique ability of WRN to bypass gaps supports its involvement in DNA replication and LP-BER where such gaps can be produced by glycosylases and the apurinic/apyrimidinic endonuclease 1 (APE1). Furthermore, we tested telomere repeat binding factor 2 (TRF2), both variants 1 and 2 of protector of telomeres 1 (POT1v1 and POT1v2) and RPA on telomeric DNA substrates containing much bigger gaps than 3-nucleotides in order to determine whether unwinding could be facilitated through WRN-protein interaction. Interestingly, POT1v1 and RPA are capable of stimulating WRN helicase on gapped DNA and 5'-overhang substrates, respectively.
Ahn
Byungchan
B
Department of Life Sciences, University of Ulsan, Ulsan, Korea.
Lee
Jae Wan
JW
Jung
Hana
H
Beck
Gad
G
Bohr
Vilhelm A
VA
D002460:Cell Line; D004247:DNA; D004261:DNA Replication; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases / Q000235:genetics*; D006801:Humans; D009690:Nucleic Acid Conformation; D053484:RecQ Helicases / Q000235:genetics*; D051716:Replication Protein A / Q000502:physiology*; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins / Q000502:physiology*; D000071657:Werner Syndrome Helicase
D029968:Escherichia coli Proteins; C440849:POT1 protein, human; C497167:RPA1 protein, human; D051716:Replication Protein A; D000089804:Shelterin Complex; D034501:Telomere-Binding Proteins; D004247:DNA; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase