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Holliday junction

Jejoong Yoo, Aleksei Aksimentiev
In contrast to ordinary polymers, the vast majority of biological macromolecules adopt highly ordered three-dimensional structures that define their functions. The key to folding of a biopolymer into a unique 3D structure or to an assembly of several biopolymers into a functional unit is a delicate balance between the attractive and repulsive forces that also makes such self-assembly reversible under physiological conditions. The all-atom molecular dynamics (MD) method has emerged as a powerful tool for studies of individual biomolecules and their functional assemblies, encompassing systems of ever increasing complexity...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
Herui Wang, Chi Zhang, Xiaowen Wang, Yaru Lian, Bin Guo, Miao Han, Xiaoe Zhang, Xiaoting Zhu, Sixian Xu, Zengli Guo, Yunli Bi, Qian Shen, Xiang Wang, Jiaojiao Liu, Yuan Zhuang, Ting Ni, Hong Xu, Xiaohui Wu
Congenital anomalies of the kidney and urinary tract (CAKUT) are among the most common developmental defects in humans. Despite of several known CAKUT-related loci ( HNF1B , PAX2 , EYA1 , etc.), the genetic etiology of CAKUT remains to be elucidated for most patients. In this study, we report that disruption of the Holliday Junction resolvase gene Gen1 leads to renal agenesis, duplex kidney, hydronephrosis, and vesicoureteral reflux (VUR) in mice. GEN1 interacts with SIX1 and enhances the transcriptional activity of SIX1/EYA1, a key regulatory complex of the GDNF morphogen...
2018: International Journal of Biological Sciences
Mehtap Danismazoglu, Remziye Nalcacioglu, Hacer Muratoglu, Zihni Demirbag
Entomopoxviruses are an important group of viruses infecting only insects. They belong to Poxviridae which infect both invertebrates and vertebrates, including humans. Protein kinases are known to have roles at virus morphogenesis, host selectivity, the regulation of cell division and apoptosis in some vertebrate poxviruses. In this study, 2 protein kinases (PKs) (AMV153 and AMV197) of Amsacta moorei entomopoxvirus (AMEV) were investigated for the interactions among 230 viral proteins using yeast two-hybrid system (Y2H)...
February 19, 2018: Virus Research
Rajvee Shah Punatar, Stephen C West
Holliday junctions provide a covalent link between recombining DNA molecules and need to be removed prior to chromosome segregation at mitosis. Defects in their resolution lead to mitotic catastrophe, characterized by the formation of DNA breaks and chromosome aberrations. Enzymes that resolve recombination intermediates have been identified in all forms of life, from bacteriophage, to bacteria, yeast, and humans. In higher eukaryotes, Holliday junctions are resolved by GEN1, a nuclease that is mechanistically similar to the prototypic resolvase Escherichia coli RuvC, and by the SMX trinuclease complex...
2018: Methods in Enzymology
Yijin Liu, Alasdair Freeman, Anne-Cécile Déclais, Anton Gartner, David M J Lilley
Four-way Holliday junctions in DNA are the central intermediates of genetic recombination and must be processed into regular duplex species. One mechanism for achieving this is called resolution, brought about by structure-selective nucleases. GEN1 is an important junction-resolving enzyme in eukaryotic cells, a member of the FEN1/EXO1 superfamily of nucleases. While human GEN1 is difficult to work with because of aggregation, orthologs from thermophilic fungi have been identified using bioinformatics and have proved to have excellent properties...
2018: Methods in Enzymology
Ying Wai Chan, Stephen C West
Successful chromosome segregation depends on the timely removal of DNA recombination and replication intermediates that interlink sister chromatids. These intermediates are acted upon by structure-selective endonucleases that promote incisions close to the junction point. GEN1, a member of the Rad2/XPG endonuclease family, was identified on the basis of its ability to cleave Holliday junction recombination intermediates. Resolution occurs by a nick and counter-nick mechanism in strands that are symmetrically related across the junction point, leading to the formation of ligatable nicked duplex products...
2018: Methods in Enzymology
Kosei Hasegawa, Yuji Ikeda, Yuko Kunugi, Akira Kurosaki, Yuichi Imai, Shunsuke Kohyama, Shoji Nagao, Eito Kozawa, Koji Yoshida, Takuya Tsunoda, Yusuke Nakamura, Keiichi Fujiwara
Cancer immunotherapy has now been established as a leading standard therapeutic option in a subset of patients with cancer. In this study, we conducted a phase I dose-escalation trial using a mixture of 5 peptides to vaccinate cervical cancer patients with HLA-A*2402. The primary endpoints were safety and determination of a recommended vaccine dose, and the secondary endpoints were evaluations of immunologic responses and clinical efficacy. All patients had recurrent or persistent disease and had failed to respond to or were intolerant to prior standard chemotherapy...
February 9, 2018: Journal of Immunotherapy
Brittany L Cannon, Lance Kenneth Patten, Donald L Kellis, Paul H Davis, Jeunghoon Lee, Elton Graugnard, Bernard Yurke, William B Knowlton
Exciton delocalization in dye aggregate systems is a phenomenon that is revealed by spectral features, such as Davydov splitting, J- and H-aggregate behavior, and fluorescence suppression. Using DNA as an architectural template to assemble dye aggregates enables specific control of the aggregate size and dye type, proximal and precise positioning of the dyes within the aggregates, and a method for constructing large, modular two- and three-dimensional arrays. Here, we report on dye aggregates, organized via an immobile Holliday junction DNA template, that exhibit large Davydov splitting of the absorbance spectrum (125 nm, 397...
February 8, 2018: Journal of Physical Chemistry. A
Yuezhou Zhang, Jing Tu, Dongqing Wang, Haitao Zhu, Sajal Kumar Maity, Xiangmeng Qu, Bram Bogaert, Hao Pei, Hongbo Zhang
DNA encodes the genetic information; recently, it has also become a key player in material science. Given the specific Watson-Crick base-pairing interactions between only four types of nucleotides, well-designed DNA self-assembly can be programmable and predictable. Stem-loops, sticky ends, Holliday junctions, DNA tiles, and lattices are typical motifs for forming DNA-based structures. The oligonucleotides experience thermal annealing in a near-neutral buffer containing a divalent cation (usually Mg2+ ) to produce a variety of DNA nanostructures...
February 1, 2018: Advanced Materials
Subhas C Bera, Tapas Paul, A N Sekar Iyengar, Padmaja P Mishra
We have investigated the isomerization dynamics and plausible energy landscape of 4-way Holliday junctions (4WHJs) bound to integration host factor (IHF, a DNA binding protein), considering the effect of applied external force, by single-molecule FRET methods. A slowing down of the forward as well as the backward rates of the isomerization process of the protein bound 4WHJ has been observed under the influence of an external force, which indicates an imposed restriction on the conformational switching. This has also been reflected by an increase in rigidity, as observed from the increase in the single-molecule FRET (smFRET)-anisotropy values (0...
January 31, 2018: Faraday Discussions
Stephen C West, Ying Wai Chan
The efficient processing of homologous recombination (HR) intermediates, which often contain four-way structures known as Holliday junctions (HJs), is required for proper chromosome segregation at mitosis. Eukaryotic cells possess three distinct pathways of resolution: (i) HJ dissolution mediated by BLM-topoisomerase IIIα-RMI1-RMI2 (BTR) complex, and HJ resolution catalyzed by either (ii) SLX1-SLX4-MUS81-EME1-XPF-ERCC1 (SMX complex) or (iii) GEN1. The BTR pathway acts at all times throughout the cell cycle, whereas the actions of SMX and GEN1 are restrained in S phase and become elevated late in the cell cycle to ensure the resolution of persistent recombination intermediates before mitotic division...
January 18, 2018: Cold Spring Harbor Symposia on Quantitative Biology
Nadish Goyal, Matthew J Rossi, Olga M Mazina, Yong Chi, Robert L Moritz, Bruce E Clurman, Alexander V Mazin
In eukaryotes, RAD54 catalyzes branch migration (BM) of Holliday junctions, a basic process during DNA repair, replication, and recombination. RAD54 also stimulates RAD51 recombinase and has other activities. Here, we investigate the structural determinants for different RAD54 activities. We find that the RAD54 N-terminal domain (NTD) is responsible for initiation of BM through two coupled, but distinct steps; specific binding to Holliday junctions and RAD54 oligomerization. Furthermore, we find that the RAD54 oligomeric state can be controlled by NTD phosphorylation at S49, a CDK2 consensus site, which inhibits RAD54 oligomerization and, consequently, BM...
January 2, 2018: Nature Communications
Thomas J Nicholls, Cristina A Nadalutti, Elisa Motori, Ewen W Sommerville, Gráinne S Gorman, Swaraj Basu, Emily Hoberg, Doug M Turnbull, Patrick F Chinnery, Nils-Göran Larsson, Erik Larsson, Maria Falkenberg, Robert W Taylor, Jack D Griffith, Claes M Gustafsson
How mtDNA replication is terminated and the newly formed genomes are separated remain unknown. We here demonstrate that the mitochondrial isoform of topoisomerase 3α (Top3α) fulfills this function, acting independently of its nuclear role as a component of the Holliday junction-resolving BLM-Top3α-RMI1-RMI2 (BTR) complex. Our data indicate that mtDNA replication termination occurs via a hemicatenane formed at the origin of H-strand replication and that Top3α is essential for resolving this structure. Decatenation is a prerequisite for separation of the segregating unit of mtDNA, the nucleoid, within the mitochondrial network...
December 14, 2017: Molecular Cell
Hongbin Chen, Qi Wang, Yuyao Yin, Shuguang Li, Deng-Ke Niu, Hui Wang
Staphylococcus aureus small colony variants (SCVs) can cause persistent infections. However, the genomes and transcriptomes of S. aureus SCVs remain poorly understood. We isolated a pair of isogenic wild-type and SCV methicillin-resistant S. aureus (MRSA) strains (IE1 and IE2, respectively) from a patient with prosthetic valve infectious endocarditis. The SCV IE2 strain grew more slowly than the wild-type strain, and serum killing and mouse lethality assays revealed that the virulence of the SCV strain IE2 was decreased...
December 13, 2017: International Journal of Antimicrobial Agents
Shun-Hsiao Lee, Tao-Shih Hsieh, Grace Ee-Lu Siaw
Hemicatenane is a structure that forms when two DNA duplexes are physically linked through a single-stranded crossover. It is proposed to be an intermediate resulting from double Holliday junction (dHJ) dissolution, repair of replication stalled forks and late stage replication. Our previous study has shown that hemicatenane can be synthesized and dissolved in vitro by hyperthermophilic type IA topoisomerases. Here we present the protocol of hemicatenane synthesis and its structure detection by 2D agarose gel electrophoresis...
2018: Methods in Molecular Biology
Noshin Afshan, Mashooq Ali, Meng Wang, Mirza Muhammad Faran Ashraf Baig, Shou-Jun Xiao
Using small circular DNA molecules of different lengths as scaffolds, we successfully synthesised DNA nanotubes consisting of Mao's DNA tensegrity triangle tiles with four-arm junctions (Holliday junctions) at all vertices. Due to the intrinsic curvature of the triangle tile and the consecutive tile alignment, the 2D arrays are organised in the form of nanotubes. Two sized triangle tiles with equilateral side lengths of 1.5 and 2.5 full helical turns are connected by the sticky ended cohesion of a duplex with a length of 2...
November 16, 2017: Nanoscale
Ana Valero-Rello, María López-Sanz, Alvaro Quevedo-Olmos, Alexei Sorokin, Silvia Ayora
Natural transformation and viral-mediated transduction are the main avenues of horizontal gene transfer in Firmicutes. Bacillus subtilis SPP1 is a generalized transducing bacteriophage. Using this lytic phage as a model, we have analyzed how viral replication and recombination systems contribute to the transfer of plasmid-borne antibiotic resistances. Phage SPP1 DNA replication relies on essential phage-encoded replisome organizer (G38P), helicase loader (G39P), hexameric replicative helicase (G40P), recombinase (G35P) and in less extent on the partially dispensable 5'→3' exonuclease (G34...
2017: Frontiers in Microbiology
Marina Raguse, Rubén Torres, Elena M Seco, Carolina Gándara, Silvia Ayora, Ralf Moeller, Juan C Alonso
The mechanisms that allow to circumvent replicative stress, and to resume DNA synthesis are poorly understood in Bacillus subtilis. To study the role of the diadenylate cyclase DisA and branch migration translocase (BMT) RadA/Sms in restarting a stalled replication fork, we nicked and broke the circular chromosome of an inert mature haploid spore, damaged the bases, and measured survival of reviving spores. During undisturbed ripening, nicks and breaks should be repaired by pathways that do not invoke long-range end resection or genetic exchange by homologous recombination, after which DNA replication might be initiated...
November 2017: DNA Repair
Arancha Sanchez, Mariana C Gadaleta, Oliver Limbo, Paul Russell
The DNA repair enzyme polynucleotide kinase/phosphatase (PNKP) protects genome integrity by restoring ligatable 5'-phosphate and 3'-hydroxyl termini at single-strand breaks (SSBs). In humans, PNKP mutations underlie the neurological disease known as MCSZ, but these individuals are not predisposed for cancer, implying effective alternative repair pathways in dividing cells. Homology-directed repair (HDR) of collapsed replication forks was proposed to repair SSBs in PNKP-deficient cells, but the critical HDR protein Rad51 is not required in PNKP-null (pnk1Δ) cells of Schizosaccharomyces pombe...
September 2017: PLoS Genetics
Fangfang Li, Lindsay G Ball, Li Fan, Michelle Hanna, Wei Xiao
DNA-damage tolerance (DDT) is employed by eukaryotes to deal with replication blocks on the template strand, and is divided into two parallel pathways that are activated by sequential ubiquitination of proliferating cell nuclear antigen (PCNA) at the Lys164 residue. Rad6-Rad18-mediated PCNA monoubiquitination promotes translesion DNA synthesis (TLS) and the monoubiquitinated PCNA can be further polyubiquitinated by an Mms2-Ubc13-Rad5 complex, leading to error-free lesion bypass. We previously reported that the DNA helicase Sgs1 is required for error-free lesion bypass, probably through the double-Holliday junction migration and subsequent resolution...
September 16, 2017: Current Genetics
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