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.
Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Dr, Baltimore, MD 21224, USA.
Cayetano
C
von Kobbe
Jeanine A
JA
Harrigan
Valérie
V
Schreiber
Patrick
P
Stiegler
Jason
J
Piotrowski
Lale
L
Dawut
Vilhelm A
VA
Bohr
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