scholarly journals DNA Processing Proteins Involved in the UV-Induced Stress Response of Sulfolobales

2015 ◽  
Vol 197 (18) ◽  
pp. 2941-2951 ◽  
Author(s):  
Marleen van Wolferen ◽  
Xiaoqing Ma ◽  
Sonja-Verena Albers
Keyword(s):  
Homologous Recombination ◽  
Uv Light ◽  
Dna Lesions ◽  
Dna Transfer ◽  
Content Type ◽  
Induced Stress ◽  
Cellular Aggregation ◽  
Uv Stress ◽  
Dna Processing

ABSTRACTTheupsoperon ofSulfolobusspecies is highly induced upon UV stress. Previous studies showed that the pili encoded by this operon are involved in cellular aggregation, which is essential for subsequent DNA exchange between cells, resulting in homologous recombination. The presence of this pilus system increases the fitness ofSulfolobuscells under UV light-induced stress conditions, as the transfer of DNA takes place in order to repair UV-induced DNA lesions via homologous recombination. Four conserved genes (saci_1497tosaci_1500) which encode proteins with putative DNA processing functions are present downstream of theupsoperon. In this study, we show that after UV treatment the cellular aggregation of strains withsaci_1497,saci_1498, andsaci_1500deletions is similar to that of wild-type strains; their survival rates, however, were reduced and similar to or lower than those of the pilus deletion strains, which could not aggregate anymore. DNA recombination assays indicated thatsaci_1498, encoding a ParB-like protein, plays an important role in DNA transfer. Moreover, biochemical analysis showed that the endonuclease III encoded bysaci_1497nicks UV-damaged DNA. In addition, RecQ-like helicase Saci_1500 is able to unwind homologous recombination intermediates, such as Holliday junctions. Interestingly, asaci_1500deletion mutant was more sensitive to UV light but not to the replication-stalling agents hydroxyurea and methyl methanesulfonate, suggesting that Saci_1500 functions specifically in the UV damage pathway. Together these results suggest a role of Saci_1497 to Saci_1500 in the repair or transfer of DNA that takes place after UV-induced damage to the genomic DNA ofSulfolobus acidocaldarius.IMPORTANCESulfolobalesspecies increase their fitness after UV stress by a UV-inducible pilus system that enables high rates of DNA exchange between cells. Downstream of the pilus operon, three genes that seem to play a role in the repair or transfer of the DNA betweenSulfolobuscells were identified, and their possible functions are discussed. Next to the previously described role of UV-inducible pili in the exchange of DNA, we have thereby increased our knowledge of DNA transfer at the level of DNA processing. This paper therefore contributes to the overall understanding of the DNA exchange mechanism amongSulfolobalescells.

UV Stimulation of Chromosomal Marker Exchange in Sulfolobus acidocaldarius: Implications for DNA Repair, Conjugation and Homologous Recombination at Extremely High Temperatures

Genetics ◽  
1999 ◽  
Vol 152 (4) ◽  
pp. 1407-1415 ◽  
Author(s):  
Katherine J Schmidt ◽  
Kristen E Beck ◽  
Dennis W Grogan
Keyword(s):  
Homologous Recombination ◽  
Incubation Temperature ◽  
Uv Light ◽  
Dna Lesions ◽  
Sulfolobus Acidocaldarius ◽  
Chromosomal Marker ◽  
Marker Exchange ◽  
Chromosomal Markers ◽  
Rate Of Decay ◽  
Uv Photoproducts

Abstract The hyperthermophilic archaeon Sulfolobus acidocaldarius exchanges and recombines chromosomal markers by a conjugational mechanism, and the overall yield of recombinants is greatly increased by previous exposure to UV light. This stimulation was studied in an effort to clarify its mechanism and that of marker exchange itself. A variety of experiments failed to identify a significant effect of UV irradiation on the frequency of cell pairing, indicating that subsequent steps are primarily affected, i.e., transfer of DNA between cells or homologous recombination. The UV-induced stimulation decayed rather quickly in parental cells during preincubation at 75°, and the rate of decay depended on the incubation temperature. Preincubation at 75° decreased the yield of recombinants neither from unirradiated parental cells nor from parental suspensions subsequently irradiated. We interpret these results as evidence that marker exchange is stimulated by recombinogenic DNA lesions formed as intermediates in the process of repairing UV photoproducts in the S. acidocaldarius chromosome.

scholarly journals De novo phosphorylation of H2AX by WSTF regulates transcription-coupled homologous recombination repair

2019 ◽  
Vol 47 (12) ◽  
pp. 6299-6314 ◽  
Author(s):  
Jae-Hoon Ji ◽  
Sunwoo Min ◽  
Sunyoung Chae ◽  
Geun-Hyoung Ha ◽  
Yonghyeon Kim ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Rna Polymerase Ii ◽  
De Novo ◽  
Dna Lesions ◽  
Proliferating Cells ◽  
Histone H2ax ◽  
Rna Transcripts ◽  
Recombination Repair ◽  
Active Transcription

Abstract Histone H2AX undergoes a phosphorylation switch from pTyr142 (H2AX-pY142) to pSer139 (γH2AX) in the DNA damage response (DDR); however, the functional role of H2AX-pY142 remains elusive. Here, we report a new layer of regulation involving transcription-coupled H2AX-pY142 in the DDR. We found that constitutive H2AX-pY142 generated by Williams-Beuren syndrome transcription factor (WSTF) interacts with RNA polymerase II (RNAPII) and is associated with RNAPII-mediated active transcription in proliferating cells. Also, removal of pre-existing H2AX-pY142 by ATM-dependent EYA1/3 phosphatases disrupts this association and requires for transcriptional silencing at transcribed active damage sites. The following recovery of H2AX-pY142 via translocation of WSTF to DNA lesions facilitates transcription-coupled homologous recombination (TC-HR) in the G1 phase, whereby RAD51 loading, but not RPA32, utilizes RNAPII-dependent active RNA transcripts as donor templates. We propose that the WSTF-H2AX-RNAPII axis regulates transcription and TC-HR repair to maintain genome integrity.

scholarly journals An IncR Plasmid Harbored by a Hypervirulent Carbapenem-Resistant Klebsiella pneumoniae Strain Possesses Five Tandem Repeats of the blaKPC-2::NTEKPC-Id Fragment

2018 ◽  
Vol 63 (3) ◽  
Author(s):  
Ning Dong ◽  
Lizhang Liu ◽  
Rong Zhang ◽  
Kaichao Chen ◽  
Miaomiao Xie ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Klebsiella Pneumoniae ◽  
Tandem Repeats ◽  
Dna Recombination ◽  
Multidrug Resistant ◽  
Plasmid Evolution ◽  
Content Type ◽  
Carbapenem Resistant

ABSTRACT Completed sequences of three plasmids from a carbapenem-resistant hypervirulent Klebsiella pneumoniae isolate, SH9, were obtained. In addition to the pLVPK-like virulence-conferring plasmid (pVir-CR-HvKP_SH9), the two multidrug-resistant plasmids (pKPC-CR-HvKP4_SH9 and pCTX-M-CR-HvKP4_SH9) were predicted to originate from a single pKPC-CR-HvKP4-like multireplicon plasmid through homologous recombination. Interestingly, the blaKPC-2 gene was detectable in five tandem repeats exhibiting the format of an NTEKPC-Id-like transposon (IS26-ΔTn3-ISKpn8-blaKPC-2-ΔISKpn6-korC-orf-IS26). The data suggest an important role of DNA recombination in mediating active plasmid evolution.

scholarly journals Role of DNA Polymerase η in the Bypass of a (6-4) TT Photoproduct

2001 ◽  
Vol 21 (10) ◽  
pp. 3558-3563 ◽  
Author(s):  
Robert E. Johnson ◽  
Lajos Haracska ◽  
Satya Prakash ◽  
Louise Prakash
Keyword(s):  
Dna Polymerase ◽  
Xeroderma Pigmentosum ◽  
Uv Light ◽  
Dna Lesions ◽  
Variant Form ◽  
Replication Machinery ◽  
Genetic Studies ◽  
Induced Mutagenesis ◽  
Combined Action

ABSTRACT UV light-induced DNA lesions block the normal replication machinery. Eukaryotic cells possess DNA polymerase η (Polη), which has the ability to replicate past a cis-syn thymine-thymine (TT) dimer efficiently and accurately, and mutations in human Polη result in the cancer-prone syndrome, the variant form of xeroderma pigmentosum. Here, we test Polη for its ability to bypass a (6-4) TT lesion which distorts the DNA helix to a much greater extent than acis-syn TT dimer. Opposite the 3′ T of a (6-4) TT photoproduct, both yeast and human Polη preferentially insert a G residue, but they are unable to extend from the inserted nucleotide. DNA Polζ, essential for UV induced mutagenesis, efficiently extends from the G residue inserted opposite the 3′ T of the (6-4) TT lesion by Polη, and Polζ inserts the correct nucleotide A opposite the 5′ T of the lesion. Thus, the efficient bypass of the (6-4) TT photoproduct is achieved by the combined action of Polη and Polζ, wherein Polη inserts a nucleotide opposite the 3′ T of the lesion and Polζ extends from it. These biochemical observations are in concert with genetic studies in yeast indicating that mutations occur predominantly at the 3′ T of the (6-4) TT photoproduct and that these mutations frequently exhibit a 3′ T→C change that would result from the insertion of a G opposite the 3′ T of the (6-4) TT lesion.

scholarly journals From Green to Red: Horizontal Gene Transfer of the Phycoerythrin Gene Cluster between Planktothrix Strains

2013 ◽  
Vol 79 (21) ◽  
pp. 6803-6812 ◽  
Author(s):  
Ave Tooming-Klunderud ◽  
Hanne Sogge ◽  
Trine Ballestad Rounge ◽  
Alexander J. Nederbragt ◽  
Karin Lagesen ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Homologous Recombination ◽  
Gene Cluster ◽  
Gene Clusters ◽  
Sequence Comparisons ◽  
Content Type ◽  
Large Gene ◽  
Dna Fragment

ABSTRACTHorizontal gene transfer is common in cyanobacteria, and transfer of large gene clusters may lead to acquisition of new functions and conceivably niche adaption. In the present study, we demonstrate that horizontal gene transfer between closely relatedPlanktothrixstrains can explain the production of the same oligopeptide isoforms by strains of different colors. Comparison of the genomes of eightPlanktothrixstrains revealed that strains producing the same oligopeptide isoforms are closely related, regardless of color. We have investigated genes involved in the synthesis of the photosynthetic pigments phycocyanin and phycoerythrin, which are responsible for green and red appearance, respectively. Sequence comparisons suggest the transfer of a functional phycoerythrin gene cluster generating a red phenotype in a strain that is otherwise more closely related to green strains. Our data show that the insertion of a DNA fragment containing the 19.7-kb phycoerythrin gene cluster has been facilitated by homologous recombination, also replacing a region of the phycocyanin operon. These findings demonstrate that large DNA fragments spanning entire functional gene clusters can be effectively transferred between closely related cyanobacterial strains and result in a changed phenotype. Further, the results shed new light on the discussion of the role of horizontal gene transfer in the sporadic distribution of large gene clusters in cyanobacteria, as well as the appearance of red and green strains.

scholarly journals Role of Mfd and GreA in Bacillus subtilis Base Excision Repair-Dependent Stationary-Phase Mutagenesis

2020 ◽  
Vol 202 (9) ◽  
Author(s):  
Hilda C. Leyva-Sánchez ◽  
Norberto Villegas-Negrete ◽  
Karen Abundiz-Yañez ◽  
Ronald E. Yasbin ◽  
Eduardo A. Robleto ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Excision Repair ◽  
Dna Lesions ◽  
Ap Endonuclease ◽  
Content Type ◽  
Error Prone Repair ◽  
Base Excision ◽  
Oxidized Guanine

ABSTRACT We report that the absence of an oxidized guanine (GO) system or the apurinic/apyrimidinic (AP) endonucleases Nfo, ExoA, and Nth promoted stress-associated mutagenesis (SAM) in Bacillus subtilis YB955 (hisC952 metB5 leuC427). Moreover, MutY-promoted SAM was Mfd dependent, suggesting that transcriptional transactions over nonbulky DNA lesions promoted error-prone repair. Here, we inquired whether Mfd and GreA, which control transcription-coupled repair and transcription fidelity, influence the mutagenic events occurring in nutritionally stressed B. subtilis YB955 cells deficient in the GO or AP endonuclease repair proteins. To this end, mfd and greA were disabled in genetic backgrounds defective in the GO and AP endonuclease repair proteins, and the strains were tested for growth-associated and stress-associated mutagenesis. The results revealed that disruption of mfd or greA abrogated the production of stress-associated amino acid revertants in the GO and nfo exoA nth strains, respectively. These results suggest that in nutritionally stressed B. subtilis cells, spontaneous nonbulky DNA lesions are processed in an error-prone manner with the participation of Mfd and GreA. In support of this notion, stationary-phase ΔytkD ΔmutM ΔmutY (referred to here as ΔGO) and Δnfo ΔexoA Δnth (referred to here as ΔAP) cells accumulated 8-oxoguanine (8-OxoG) lesions, which increased significantly following Mfd disruption. In contrast, during exponential growth, disruption of mfd or greA increased the production of His+, Met+, or Leu+ prototrophs in both DNA repair-deficient strains. Thus, in addition to unveiling a role for GreA in mutagenesis, our results suggest that Mfd and GreA promote or prevent mutagenic events driven by spontaneous genetic lesions during the life cycle of B. subtilis. IMPORTANCE In this paper, we report that spontaneous genetic lesions of an oxidative nature in growing and nutritionally stressed B. subtilis strain YB955 (hisC952 metB5 leuC427) cells drive Mfd- and GreA-dependent repair transactions. However, whereas Mfd and GreA elicit faithful repair events during growth to maintain genome fidelity, under starving conditions, both factors promote error-prone repair to produce genetic diversity, allowing B. subtilis to escape from growth-limiting conditions.

scholarly journals Role of the homologous recombination genes RAD51 and RAD59 in the resistance of Candida albicans to UV light, radiomimetic and anti-tumor compounds and oxidizing agents

2010 ◽  
Vol 47 (5) ◽  
pp. 433-445 ◽  
Author(s):  
Fátima García-Prieto ◽  
Jonathan Gómez-Raja ◽  
Encarnación Andaluz ◽  
Richard Calderone ◽  
Germán Larriba
Keyword(s):  
Candida Albicans ◽  
Homologous Recombination ◽  
Uv Light ◽  
Oxidizing Agents

scholarly journals Sister Chromatid Exchanges Are Mediated by Homologous Recombination in Vertebrate Cells

1999 ◽  
Vol 19 (7) ◽  
pp. 5166-5169 ◽  
Author(s):  
Eiichiro Sonoda ◽  
Masao S. Sasaki ◽  
Ciaran Morrison ◽  
Yuko Yamaguchi-Iwai ◽  
Minoru Takata ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Sister Chromatid ◽  
Sister Chromatid Exchanges ◽  
Dna Lesions ◽  
End Joining ◽  
Chromosomal Stability ◽  
Tumorigenic Potential ◽  
Associated Proteins ◽  
Chromatid Exchanges

ABSTRACT Sister chromatid exchange (SCE) frequency is a commonly used index of chromosomal stability in response to environmental or genetic mutagens. However, the mechanism generating cytologically detectable SCEs and, therefore, their prognostic value for chromosomal stability in mitotic cells remain unclear. We examined the role of the highly conserved homologous recombination (HR) pathway in SCE by measuring SCE levels in HR-defective vertebrate cells. Spontaneous and mitomycin C-induced SCE levels were significantly reduced for chicken DT40 B cells lacking the key HR genes RAD51 and RAD54but not for nonhomologous DNA end-joining (NHEJ)-defectiveKU70 −/− cells. As measured by targeted integration efficiency, reconstitution of HR activity by expression of a human RAD51 transgene restored SCE levels to normal, confirming that HR is the mechanism responsible for SCE. Our findings show that HR uses the nascent sister chromatid to repair potentially lethal DNA lesions accompanying replication, which might explain the lethality or tumorigenic potential associated with defects in HR or HR-associated proteins.

Long-term management of patients with multiple brain metastases after shaped beam radiosurgery

2004 ◽  
pp. 406-412
Author(s):  
Paul Okunieff ◽  
Michael C. Schell ◽  
Russell Ruo ◽  
E. Ronald Hale ◽  
Walter G. O'Dell ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Tumor Control ◽  
Content Type ◽  
Negative Results ◽  
Multiple Metastases ◽  
Extracranial Disease ◽  
Successful Control ◽  
The Brain

✓ The role of radiosurgery in the treatment of patients with advanced-stage metastatic disease is currently under debate. Previous randomized studies have not consistently supported the use of radiosurgery to treat patients with numbers of brain metastases. In negative-results studies, however, intracranial tumor control was high but extracranial disease progressed; thus, patient survival was not greatly affected, although neurocognitive function was generally maintained until death. Because the future promises improved systemic (extracranial) therapy, the successful control of brain disease is that much more crucial. Thus, for selected patients with multiple metastases to the brain who remain in good neurological condition, aggressive lesion-targeting radiosurgery should be very useful. Although a major limitation to success of this therapy is the lack of control of extracranial disease in most patients, it is clear that well-designed, aggressive treatment substantially decreases the progression of brain metastases and also improves neurocognitive survival. The authors present the management and a methodology for rational treatment of a patient with breast cancer who has harbored 24 brain metastases during a 3-year period.

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