Poly(ADP-ribose) polymerase 1 regulates both the exonuclease and helicase activities of the Werner syndrome protein.
Werner syndrome (WS) is a genetic premature aging disorder in which patients appear much older than their chronological age. The gene mutated in WS encodes a nuclear protein (WRN) which possesses 3'-5' exonuclease and ATPase-dependent 3'-5' helicase activities. The genomic instability associated with WS cells and the biochemical characteristics of WRN suggest that WRN plays a role in DNA metabolic pathways such as transcription, replication, recombination and repair. Recently we have identified poly(ADP-ribose) polymerase-1 (PARP-1) as a new WRN interacting protein. In this paper, we further mapped the interacting domains. We found that PARP-1 bound to the N-terminus of WRN and to the C-terminus containing the RecQ-conserved (RQC) domain. WRN bound to the N-terminus of PARP-1 containing DNA binding and BRCA1 C-terminal (BRCT) domains. We show that unmodified PARP-1 inhibited both WRN exonuclease and helicase activities, and to our knowledge is the only known WRN protein partner that inactivates both of the WRN's catalytic activities suggesting a biologically significant regulation. Moreover, this dual inhibition seems to be specific for PARP-1, as PARP-2 did not affect WRN helicase activity and only slightly inhibited WRN exonuclease activity. The differential effect of PARP-1 and PARP-2 on WRN catalytic activity was not due to differences in affinity for WRN or the DNA substrate. Finally, we demonstrate that the inhibition of WRN by PARP-1 was influenced by the poly(ADP-ribosyl)ation state of PARP-1. The biological relevance of the specific modulation of WRN catalytic activities by PARP-1 are discussed in the context of pathways in which these proteins may function together, namely in the repair of DNA strand breaks.
von Kobbe
Cayetano
C
Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Dr, Baltimore, MD 21224, USA.
Harrigan
Jeanine A
JA
Schreiber
Valérie
V
Stiegler
Patrick
P
Piotrowski
Jason
J
Dawut
Lale
L
Bohr
Vilhelm A
VA
D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D005090:Exodeoxyribonucleases; D005092:Exonucleases / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary; D053484:RecQ Helicases; D000071657:Werner Syndrome Helicase
D004247:DNA; D011065:Poly(ADP-ribose) Polymerases; C459820:Parp2 protein, mouse; D005090:Exodeoxyribonucleases; D005092:Exonucleases; D004265:DNA Helicases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase