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Query: EC:2.4.2.30 (
PARP
)
13,611
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
To examine the interaction of mammalian base excision repair (BER) enzymes with DNA intermediates formed during BER, we used a novel photoaffinity labeling probe and mouse embryonic fibroblast cellular extracts. The probe was formed in situ, using an end-labeled oligonucleotide containing a synthetic abasic site; this site was incised by apurinic/apyrimidinic endonuclease creating a nick with 3'-hydroxyl and 5'-reduced sugar phosphate groups at the margins, and then a dNMP carrying a photoreactive adduct was added to the 3'-hydroxyl group. With near-UV light (312 nm) exposure of the extract/probe mixture, six proteins were strongly labeled. Four of these include poly(ADP-ribose) polymerase-1 (
PARP-1
) and the BER participants
flap endonuclease-1
, DNA polymerase beta, and apurinic/apyrimidinic endonuclease. The amount of the probe cross-linked to
PARP-1
was greater than that cross-linked to the other proteins. The specificity of
PARP-1
labeling was examined using various competitor oligonucleotides and DNA probes with alternate structures.
PARP-1
labeling was stronger with a DNA representing a BER intermediate than with a nick in double-stranded DNA. These results indicate that proteins interacting preferentially with a photoreactive BER intermediate can be selected from the crude cellular extract.
...
PMID:Photoaffinity labeling of mouse fibroblast enzymes by a base excision repair intermediate. Evidence for the role of poly(ADP-ribose) polymerase-1 in DNA repair. 1134 72
Recently, photoaffinity labeling experiments with mouse cell extracts suggested that
PARP-1
functions as a surveillance protein for a stalled BER intermediate. To further understand the role of
PARP-1
in BER, we examined the DNA synthesis and flap excision steps in long patch BER using a reconstituted system containing a 34-base pair BER substrate and five purified human enzymes: uracil-DNA glycosylase, apurinic/apyrimidinic endonuclease, DNA polymerase beta,
flap endonuclease-1
(
FEN-1
), and
PARP-1
.
PARP-1
stimulates strand displacement DNA synthesis by DNA polymerase beta in this system; this stimulation is dependent on the presence of
FEN-1
.
PARP-1
and
FEN-1
, therefore, cooperate to activate long patch BER. The results are discussed in the context of a model for BER sub-pathway choice, illustrating a dual role for
PARP-1
as a surveillance protein for a stalled BER intermediate and an activating factor for long patch BER DNA synthesis.
...
PMID:DNA polymerase beta -mediated long patch base excision repair. Poly(ADP-ribose)polymerase-1 stimulates strand displacement DNA synthesis. 1144 Sep 97
DNA base excision repair (BER) constitutes a major mechanism to restore the integrity of the genome following modifications of nucleobases. Although it is well established that poly(ADP-ribosylation) facilitates BER, the mechanism of this stimulation has remained unknown. Previous observations suggested that poly(ADP-ribose), which is synthesised from NAD(+), could serve as a unique source of ATP required for the ligation step in BER. This pathway of ATP generation is thought to compensate ATP shortage and relies on the release of pyrophosphate during DNA repair synthesis. Here, we present evidence that, in situations of cellular energy depletion, the synthesis of poly(ADP-ribose) is indeed stimulated. Simultaneously, single nucleotide repair is reduced. Rather, the number of nucleotides incorporated by DNA polymerase beta (Pol beta) during DNA repair synthesis is increased. Using a reconstituted system including the recombinant BER proteins Pol beta, AP endonuclease 1 (APE 1), X-ray repair cross-complementing group-1 (XRCC1), DNA ligase III (Lig III),
flap endonuclease 1
(FEN 1), and poly(ADP-ribose) polymerase-1 (
PARP-1
), it is demonstrated that in the absence of ATP, both long patch DNA synthesis by Pol beta and poly(ADP-ribosylation) catalysed by
PARP-1
are stimulated. Consequently, the preferred use of either long patch or single nucleotide BER depends on the availability of ATP. It is proposed that long patch BER is required for ATP generation from poly(ADP-ribose) and, therefore, predominant under conditions of ATP shortage.
...
PMID:ATP-dependent selection between single nucleotide and long patch base excision repair. 1367 48
Condensins are essential protein complexes critical for mitotic chromosome organization. Little is known about the function of condensins during interphase, particularly in mammalian cells. Here we report the interphase-specific interaction between condensin I and the DNA nick-sensor poly(ADP-ribose) polymerase 1 (
PARP-1
). We show that the association between condensin I,
PARP-1
, and the base excision repair (BER) factor XRCC1 increases dramatically upon single-strand break damage (SSB) induction. Damage-specific association of condensin I with the BER factors
flap endonuclease 1
(
FEN-1
) and DNA polymerase delta/epsilon was also observed, suggesting that condensin I is recruited to interact with BER factors at damage sites. Consistent with this, DNA damage rapidly stimulates the chromatin association of
PARP-1
, condensin I, and XRCC1. Furthermore, depletion of condensin in vivo compromises SSB but not double-strand break (DSB) repair. Our results identify a SSB-specific response of condensin I through
PARP-1
and demonstrate a role for condensin in SSB repair.
...
PMID:Condensin I interacts with the PARP-1-XRCC1 complex and functions in DNA single-strand break repair. 1654 52
Flap endonuclease 1
(
FEN1
) is a structure selective endonuclease required for proficient DNA replication and the repair of DNA damage. Cellularly active inhibitors of this enzyme have previously been shown to induce a DNA damage response and, ultimately, cell death. High-throughput screens of human cancer cell-lines identify colorectal and gastric cell-lines with microsatellite instability (MSI) as enriched for cellular sensitivity to N-hydroxyurea series inhibitors of
FEN1
, but not the
PARP
inhibitor olaparib or other inhibitors of the DNA damage response. This sensitivity is due to a synthetic lethal interaction between
FEN1
and MRE11A, which is often mutated in MSI cancers through instabilities at a poly(T) microsatellite repeat. Disruption of ATM is similarly synthetic lethal with
FEN1
inhibition, suggesting that disruption of
FEN1
function leads to the accumulation of DNA double-strand breaks. These are likely a result of the accumulation of aberrant replication forks, that accumulate as a consequence of a failure in Okazaki fragment maturation, as inhibition of
FEN1
is toxic in cells disrupted for the Fanconi anemia pathway and post-replication repair. Furthermore, RAD51 foci accumulate as a consequence of
FEN1
inhibition and the toxicity of
FEN1
inhibitors increases in cells disrupted for the homologous recombination pathway, suggesting a role for homologous recombination in the resolution of damage induced by
FEN1
inhibition. Finally,
FEN1
appears to be required for the repair of damage induced by olaparib and cisplatin within the Fanconi anemia pathway, and may play a role in the repair of damage associated with its own disruption.
...
PMID:Small molecule inhibitors uncover synthetic genetic interactions of human flap endonuclease 1 (FEN1) with DNA damage response genes. 2862 39
