scholarly journals p48 Activates a UV-Damaged-DNA Binding Factor and Is Defective in Xeroderma Pigmentosum Group E Cells That Lack Binding Activity

1998 ◽  
Vol 18 (7) ◽  
pp. 4391-4399 ◽  
Author(s):  
Byung Joon Hwang ◽  
Stephanie Toering ◽  
Uta Francke ◽  
Gilbert Chu
Keyword(s):  
Xeroderma Pigmentosum ◽  
Chromosome Region ◽  
Binding Activity ◽  
Single Amino Acid ◽  
Cyclobutane Pyrimidine Dimers ◽  
Pyrimidine Dimers ◽  
Binding Factor ◽  
Hit And Run ◽  
Damaged Dna

ABSTRACT A subset of xeroderma pigmentosum (XP) group E cells lack a factor that binds to DNA damaged by UV radiation. This factor can be purified to homogeneity as p125, a 125-kDa polypeptide. However, when cDNA encoding p125 is translated in vitro, only a small fraction binds to UV-damaged DNA, suggesting that a second factor is required for the activation of p125. We discovered that most hamster cell lines expressed inactive p125, which was activated in somatic cell hybrids containing human chromosome region 11p11.2-11cen. This region excludedp125 but included p48, which encodes a 48-kDa polypeptide known to copurify with p125 under some conditions. Expression of human p48 activated p125 binding in hamster cells and increased p125 binding in human cells. No such effects were observed from expression of p48 containing single amino acid substitutions from XP group E cells that lacked binding activity, demonstrating that the p48 gene is defective in those cells. Activation of p125 occurred by a “hit-and-run” mechanism, since the presence of p48 was not required for subsequent binding. Nevertheless, p48 was capable of forming a complex with p125 either bound to UV-damaged DNA or in free solution. It is notable that hamster cells fail to efficiently repair cyclobutane pyrimidine dimers in nontranscribed DNA and fail to express p48, which contains a WD motif with homology to proteins that reorganize chromatin. We propose that p48 plays a role in repairing lesions that would otherwise remain inaccessible in nontranscribed chromatin.

scholarly journals Evidence that xeroderma pigmentosum cells from complementation group E are deficient in a homolog of yeast photolyase.

1989 ◽  
Vol 9 (11) ◽  
pp. 5105-5112 ◽  
Author(s):  
M Patterson ◽  
G Chu
Keyword(s):  
Xeroderma Pigmentosum ◽  
Excision Repair ◽  
Complementation Group ◽  
Binding Activity ◽  
Multiple Forms ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Lesion ◽  
Pyrimidine Dimers ◽  
Binding Factor ◽  
Damaged Dna

Xeroderma pigmentosum (XP) patients are deficient in the excision repair of damaged DNA. Recognition of the DNA lesion appears to involve a nuclear factor that is defective in complementation group E (XPE binding factor). We have now identified a factor in the yeast Saccharomyces cerevisiae that shares many properties with XPE binding factor, including cellular location, abundance, magnesium dependence, and relative affinities for multiple forms of damaged DNA. Yeast binding activity is dependent on photolyase, which catalyzes the photoreactivation of pyrimidine dimers. These results suggest that yeast photolyase may also function as an auxiliary protein in excision repair. Furthermore, XPE binding factor appears to be the human homolog of yeast photolyase.

Evidence that xeroderma pigmentosum cells from complementation group E are deficient in a homolog of yeast photolyase

1989 ◽  
Vol 9 (11) ◽  
pp. 5105-5112
Author(s):  
M Patterson ◽  
G Chu
Keyword(s):  
Xeroderma Pigmentosum ◽  
Excision Repair ◽  
Complementation Group ◽  
Binding Activity ◽  
Multiple Forms ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Lesion ◽  
Pyrimidine Dimers ◽  
Binding Factor ◽  
Damaged Dna

Xeroderma pigmentosum (XP) patients are deficient in the excision repair of damaged DNA. Recognition of the DNA lesion appears to involve a nuclear factor that is defective in complementation group E (XPE binding factor). We have now identified a factor in the yeast Saccharomyces cerevisiae that shares many properties with XPE binding factor, including cellular location, abundance, magnesium dependence, and relative affinities for multiple forms of damaged DNA. Yeast binding activity is dependent on photolyase, which catalyzes the photoreactivation of pyrimidine dimers. These results suggest that yeast photolyase may also function as an auxiliary protein in excision repair. Furthermore, XPE binding factor appears to be the human homolog of yeast photolyase.

scholarly journals The Naturally Occurring Mutants of DDB Are Impaired in Stimulating Nuclear Import of the p125 Subunit and E2F1-Activated Transcription

1999 ◽  
Vol 19 (7) ◽  
pp. 4935-4943 ◽  
Author(s):  
Pavel Shiyanov ◽  
Steven A. Hayes ◽  
Manjula Donepudi ◽  
Anne F. Nichols ◽  
Stuart Linn ◽  
...  
Keyword(s):  
Dna Binding ◽  
Critical Role ◽  
Binding Activity ◽  
Single Amino Acid ◽  
Nuclear Accumulation ◽  
Stable Complex ◽  
Deficiency Disease ◽  
Naturally Occurring ◽  
Repair Deficiency ◽  
Damaged Dna

ABSTRACT The human UV-damaged-DNA binding protein DDB has been linked to the repair deficiency disease xeroderma pigmentosum group E (XP-E), because a subset of XP-E patients lack the damaged-DNA binding function of DDB. Moreover, the microinjection of purified DDB complements the repair deficiency in XP-E cells lacking DDB. Two naturally occurring XP-E mutations of DDB, 82TO and 2RO, have been characterized. They have single amino acid substitutions (K244E and R273H) within the WD motif of the p48 subunit of DDB, and the mutated proteins lack the damaged-DNA binding activity. In this report, we describe a new function of the p48 subunit of DDB, which reveals additional defects in the function of the XP-E mutants. We show that when the subunits of DDB were expressed individually, p48 localized in the nucleus and p125 localized in the cytoplasm. The coexpression of p125 with p48 resulted in an increased accumulation of p125 in the nucleus, indicating that p48 plays a critical role in the nuclear localization of p125. The mutant forms of p48, 2RO and 82TO, are deficient in stimulating the nuclear accumulation of the p125 subunit of DDB. In addition, the mutant 2RO fails to form a stable complex with the p125 subunit of DDB. Our previous studies indicated that DDB can associate with the transcription factor E2F1 and can function as a transcriptional partner of E2F1. Here we show that the two mutants, while they associate with E2F1 as efficiently as wild-type p48, are severely impaired in stimulating E2F1-activated transcription. This is consistent with our observation that both subunits of DDB are required to stimulate E2F1-activated transcription. The results provide insights into the functions of the subunits of DDB and suggest a possible link between the role of DDB in E2F1-activated transcription and the repair deficiency disease XP-E.

scholarly journals Increased UV resistance of a xeroderma pigmentosum revertant cell line is correlated with selective repair of the transcribed strand of an expressed gene.

1993 ◽  
Vol 13 (2) ◽  
pp. 970-976 ◽  
Author(s):  
L Lommel ◽  
P C Hanawalt
Keyword(s):  
Cell Line ◽  
Dihydrofolate Reductase ◽  
Xeroderma Pigmentosum ◽  
Uv Resistance ◽  
Cyclobutane Pyrimidine Dimers ◽  
Pyrimidine Dimers ◽  
Reductase Gene ◽  
Group A ◽  
A Cell ◽  
Xeroderma Pigmentosum Group A

A UV-resistant revertant (XP129) of a xeroderma pigmentosum group A cell line has been reported to be totally deficient in repair of cyclobutane pyrimidine dimers (CPDs) but proficient in repair of 6-4 photoproducts. This finding has been interpreted to mean that CPDs play no role in cell killing by UV. We have analyzed the fine structure of repair of CPDs in the dihydrofolate reductase gene in the revertant. In this essential, active gene, we observe that repair of the transcribed strand is as efficient as that in normal, repair-proficient human cells, but repair of the nontranscribed strand is not. Within 4 h after UV at 7.5 J/m2, over 50% of the CPDs were removed, and by 8 h, 80% of the CPDs were removed. In contrast, there was essentially no removal from the nontranscribed strand even by 24 h. Our results demonstrate that overall repair measurements can be misleading, and they support the hypothesis that removal of CPDs from the transcribed strands of expressed genes is essential for UV resistance.

scholarly journals Spore Photoproduct (SP) Lyase from Bacillus subtilisSpecifically Binds to and Cleaves SP (5-Thyminyl-5,6-Dihydrothymine) but Not Cyclobutane Pyrimidine Dimers in UV-Irradiated DNA

2000 ◽  
Vol 182 (22) ◽  
pp. 6412-6417 ◽  
Author(s):  
Tony A. Slieman ◽  
Roberto Rebeil ◽  
Wayne L. Nicholson
Keyword(s):  
Factor Xa ◽  
Dnase I ◽  
Single Pair ◽  
Cyclobutane Pyrimidine Dimers ◽  
Dnase I Footprinting ◽  
Pyrimidine Dimers ◽  
Spore Photoproduct ◽  
Helical Turn ◽  
Overexpression System

The predominant photolesion in the DNA of UV-irradiated dormant bacterial spores is the thymine dimer 5-thyminyl-5,6-dihydrothymine, commonly referred to as spore photoproduct (SP). A major determinant of SP repair during spore germination is its direct reversal by the enzyme SP lyase, encoded by the splB gene in Bacillus subtilis. SplB protein containing an N-terminal tag of six histidine residues [(6His)SplB] was purified from dormant B. subtilis spores and shown to efficiently cleave SP but not cyclobutane cis,syn thymine-thymine dimers in vitro. In contrast, SplB protein containing an N-terminal 10-histidine tag [(10His)SplB] purified from an Escherichia colioverexpression system was incompetent to cleave SP unless the 10-His tag was first removed by proteolysis at an engineered factor Xa site. To assay the parameters of binding of SplB protein to UV-damaged DNA, a 35-bp double-stranded oligonucleotide was constructed which carried a single pair of adjacent thymines on one strand. Irradiation of the oligonucleotide in aqueous solution or at 10% relative humidity resulted in formation of cyclobutane pyrimidine dimers (Py◊Py) or SP, respectively. (10His)SplB was assayed for oligonucleotide binding using a DNase I protection assay. In the presence of (10His)SplB, the SP-containing oligonucleotide was selectively protected from DNase I digestion (half-life, >60 min), while the Py◊Py-containing oligonucleotide and the unirradiated oligonucleotide were rapidly digested by DNase I (half-lives, 6 and 9 min, respectively). DNase I footprinting of (10His)SplB bound to the artificial substrate was carried out utilizing the 32P end-labeled 35-bp oligonucleotide containing SP. DNase I footprinting showed that SplB protected at least a 9-bp region surrounding SP from digestion with DNase I with the exception of two DNase I-hypersensitive sites within the protected region. (10His)SplB also caused significant enhancement of DNase I digestion of the SP-containing oligonucleotide for at least a full helical turn 3′ to the protected region. The data suggest that binding of SP lyase to SP causes significant bending or distortion of the DNA helix in the vicinity of the lesion.

scholarly journals An alternative eukaryotic DNA excision repair pathway.

1995 ◽  
Vol 15 (8) ◽  
pp. 4572-4577 ◽  
Author(s):  
G A Freyer ◽  
S Davey ◽  
J V Ferrer ◽  
A M Martin ◽  
D Beach ◽  
...  
Keyword(s):  
Dna Repair ◽  
Excision Repair ◽  
Uv Light ◽  
Repair Process ◽  
Dna Lesions ◽  
Repair Pathway ◽  
Cyclobutane Pyrimidine Dimers ◽  
Dna Excision Repair ◽  
Pyrimidine Dimers

DNA lesions induced by UV light, cyclobutane pyrimidine dimers, and (6-4)pyrimidine pyrimidones are known to be repaired by the process of nucleotide excision repair (NER). However, in the fission yeast Schizosaccharomyces pombe, studies have demonstrated that at least two mechanisms for excising UV photo-products exist; NER and a second, previously unidentified process. Recently we reported that S. pombe contains a DNA endonuclease, SPDE, which recognizes and cleaves at a position immediately adjacent to cyclobutane pyrimidine dimers and (6-4)pyrimidine pyrimidones. Here we report that the UV-sensitive S. pombe rad12-502 mutant lacks SPDE activity. In addition, extracts prepared from the rad12-502 mutant are deficient in DNA excision repair, as demonstrated in an in vitro excision repair assay. DNA repair activity was restored to wild-type levels in extracts prepared from rad12-502 cells by the addition of partially purified SPDE to in vitro repair reaction mixtures. When the rad12-502 mutant was crossed with the NER rad13-A mutant, the resulting double mutant was much more sensitive to UV radiation than either single mutant, demonstrating that the rad12 gene product functions in a DNA repair pathway distinct from NER. These data directly link SPDE to this alternative excision repair process. We propose that the SPDE-dependent DNA repair pathway is the second DNA excision repair process present in S. pombe.

scholarly journals Phosphorylation of TFIIA Stimulates TATA Binding Protein-TATA Interaction and Contributes to Maximal Transcription and Viability in Yeast

1999 ◽  
Vol 19 (4) ◽  
pp. 2846-2852 ◽  
Author(s):  
Steven P. Solow ◽  
Larissa Lezina ◽  
Paul M. Lieberman
Keyword(s):  
Binding Protein ◽  
Large Subunit ◽  
Tata Binding Protein ◽  
Binding Activity ◽  
Single Amino Acid ◽  
Stable Complex ◽  
Alanine Substitution ◽  
High Level

ABSTRACT Posttranslational modification of general transcription factors may be an important mechanism for global gene regulation. The general transcription factor IIA (TFIIA) binds to the TATA binding protein (TBP) and is essential for high-level transcription mediated by various activators. Modulation of the TFIIA-TBP interaction is a likely target of transcriptional regulation. We report here that Toa1, the large subunit of yeast TFIIA, is phosphorylated in vivo and that this phosphorylation stabilizes the TFIIA-TBP-DNA complex and is required for high-level transcription. Alanine substitution of serine residues 220, 225, and 232 completely eliminated in vivo phosphorylation of Toa1, although no single amino acid substitution of these serine residues eliminated phosphorylation in vivo. Phosphorylated TFIIA was 30-fold more efficient in forming a stable complex with TBP and TATA DNA. Dephosphorylation of yeast-derived TFIIA reduced DNA binding activity, and recombinant TFIIA could be stimulated by in vitro phosphorylation with casein kinase II. Yeast strains expressing thetoa1 S220/225/232A showed reduced high-level transcriptional activity at the URA1, URA3, andHIS3 promoters but were viable. However, S220/225/232A was synthetically lethal when combined with an alanine substitution mutation at W285, which disrupts the TFIIA-TBP interface. Phosphorylation of TFIIA could therefore be an important mechanism of transcription modulation, since it stimulates TFIIA-TBP association, enhances high-level transcription, and contributes to yeast viability.

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