scholarly journals Cockayne Syndrome B protein selectively interacts and resolves intermolecular DNA G-quadruplex structures

2021 ◽  
Author(s):  
Denise Liano ◽  
Marco Di Antonio
Keyword(s):  
Ribosomal Dna ◽  
Living Cells ◽  
Cockayne Syndrome ◽  
Biological Functions ◽  
Loss Of Function ◽  
Endogenous Protein ◽  
G Quadruplex ◽  
Dna Strands ◽  
Low Probability ◽  
Dna Strand

AbstractGuanine-rich DNA can fold into secondary structures known as G-quadruplexes (G4s). G4s can form from a single DNA-strand (intramolecular) or from multiple DNA-strands (intermolecular), but studies on their biological functions have been often limited to intramolecular G4s, owing to the low probability of intermolecular G4s to form within genomic DNA. Herein, we report that the endogenous protein Cockayne Syndrome B (CSB) binds with picomolar affinity to intermolecular G4s, whilst displaying negligible binding towards intramolecular structures. We also observed that CSB can selectively resolve intermolecular G4s in an ATP independent fashion. Our study demonstrates that intermolecular G4s formed within ribosomal DNA are natural substrates for CSB, strongly suggesting that these structures might be formed in the nucleolus of living cells. Given that CSB loss of function elicits premature ageing phenotypes, our findings indicate that the interaction between CSB and ribosomal DNA intermolecular G4s is essential to maintain cellular homeostasis.

scholarly journals Cockayne syndrome group A and B proteins converge on transcription-linked resolution of non-B DNA

2016 ◽  
Vol 113 (44) ◽  
pp. 12502-12507 ◽  
Author(s):  
Morten Scheibye-Knudsen ◽  
Anne Tseng ◽  
Martin Borch Jensen ◽  
Karsten Scheibye-Alsing ◽  
Evandro Fei Fang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mitochondrial Dysfunction ◽  
Ribosomal Dna ◽  
Neuroblastoma Cell ◽  
Accelerated Aging ◽  
Neuroblastoma Cell Line ◽  
Cockayne Syndrome ◽  
Rdna Transcription ◽  
Dna Transcription ◽  
G Quadruplex

Cockayne syndrome is a neurodegenerative accelerated aging disorder caused by mutations in the CSA or CSB genes. Although the pathogenesis of Cockayne syndrome has remained elusive, recent work implicates mitochondrial dysfunction in the disease progression. Here, we present evidence that loss of CSA or CSB in a neuroblastoma cell line converges on mitochondrial dysfunction caused by defects in ribosomal DNA transcription and activation of the DNA damage sensor poly-ADP ribose polymerase 1 (PARP1). Indeed, inhibition of ribosomal DNA transcription leads to mitochondrial dysfunction in a number of cell lines. Furthermore, machine-learning algorithms predict that diseases with defects in ribosomal DNA (rDNA) transcription have mitochondrial dysfunction, and, accordingly, this is found when factors involved in rDNA transcription are knocked down. Mechanistically, loss of CSA or CSB leads to polymerase stalling at non-B DNA in a neuroblastoma cell line, in particular at G-quadruplex structures, and recombinant CSB can melt G-quadruplex structures. Indeed, stabilization of G-quadruplex structures activates PARP1 and leads to accelerated aging in Caenorhabditis elegans. In conclusion, this work supports a role for impaired ribosomal DNA transcription in Cockayne syndrome and suggests that transcription-coupled resolution of secondary structures may be a mechanism to repress spurious activation of a DNA damage response.

scholarly journals Cockayne syndrome B protein acts as an ATP-dependent processivity factor that helps RNA polymerase II overcome nucleosome barriers

2020 ◽  
Vol 117 (41) ◽  
pp. 25486-25493 ◽  
Author(s):  
Jun Xu ◽  
Wei Wang ◽  
Liang Xu ◽  
Jia-Yu Chen ◽  
Jenny Chong ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Neurological Diseases ◽  
Transcription Elongation ◽  
Cockayne Syndrome ◽  
Stable Complex ◽  
Loss Of Function ◽  
Pol Ii ◽  
Chromatin Remodelers ◽  
Processivity Factor

While loss-of-function mutations in Cockayne syndrome group B protein (CSB) cause neurological diseases, this unique member of the SWI2/SNF2 family of chromatin remodelers has been broadly implicated in transcription elongation and transcription-coupled DNA damage repair, yet its mechanism remains largely elusive. Here, we use a reconstituted in vitro transcription system with purified polymerase II (Pol II) and Rad26, a yeast ortholog of CSB, to study the role of CSB in transcription elongation through nucleosome barriers. We show that CSB forms a stable complex with Pol II and acts as an ATP-dependent processivity factor that helps Pol II across a nucleosome barrier. This noncanonical mechanism is distinct from the canonical modes of chromatin remodelers that directly engage and remodel nucleosomes or transcription elongation factors that facilitate Pol II nucleosome bypass without hydrolyzing ATP. We propose a model where CSB facilitates gene expression by helping Pol II bypass chromatin obstacles while maintaining their structures.

scholarly journals 3′ → 5′ Exonucleases of DNA Polymerases ϵ and δ Correct Base Analog Induced DNA Replication Errors on Opposite DNA Strands in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 717-726 ◽  
Author(s):  
Polina V Shcherbakova ◽  
Youri I Pavlov
Keyword(s):  
Dna Replication ◽  
Dna Polymerases ◽  
Replication Errors ◽  
Dna Strands ◽  
Base Analog ◽  
Chromosome Iii ◽  
Dna Strand ◽  
Dna Replication Errors ◽  
Yeast Mutants ◽  
Lagging Strand

Abstract The base analog 6-N-hydroxylaminopurine (HAP) induces bidirectional GC → AT and AT → GC transitions that are enhanced in DNA polymerase ϵ and δ 3′ → 5′ exonuclease-deficient yeast mutants, pol2-4 and pol3-01, respectively. We have constructed a set of isogenic strains to determine whether the DNA polymerases δ and ϵ contribute equally to proofreading of replication errors provoked by HAP during leading and lagging strand DNA synthesis. Site-specific GC → AT and AT → GC transitions in a Pol→, pol2-4 or pol3-01 genetic background were scored as reversions of ura3 missense alleles. At each site, reversion was increased in only one proofreading-deficient mutant, either pol2-4 or pol3-01, depending on the DNA strand in which HAP incorporation presumably occurred. Measurement of the HAP-induced reversion frequency of the ura3 alleles placed into chromosome III near to the defined active replication origin ARS306 in two orientations indicated that DNA polymerases ϵ and δ correct HAP-induced DNA replication errors on opposite DNA strands.

scholarly journals Stablization of ACOs by NatB mediated N-terminal acetylation is required for ethylene homeostasis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hai-qing Liu ◽  
Ya-jie Zou ◽  
Xiao-feng Li ◽  
Lei Wu ◽  
Guang-qin Guo
Keyword(s):  
Protein Modification ◽  
Normal Growth ◽  
Ethylene Biosynthesis ◽  
Regulation Mechanism ◽  
Biological Functions ◽  
Loss Of Function ◽  
Auxiliary Subunit ◽  
Ethylene Content ◽  
Endogenous Ethylene ◽  
Exogenous Ethylene

AbstractN-terminal acetylation (NTA) is a highly abundant protein modification catalyzed by N-terminal acetyltransferases (NATs) in eukaryotes. However, the plant NATs and their biological functions have been poorly explored. Here we reveal that loss of function of CKRC3 and NBC-1, the auxiliary subunit (Naa25) and catalytic subunit (Naa20) of Arabidopsis NatB, respectively, led to defects in skotomorphogenesis and triple responses of ethylene. Proteome profiling and WB test revealed that the 1-amincyclopropane-1-carboxylate oxidase (ACO, catalyzing the last step of ethylene biosynthesis pathway) activity was significantly down-regulated in natb mutants, leading to reduced endogenous ethylene content. The defective phenotypes could be fully rescued by application of exogenous ethylene, but less by its precursor ACC. The present results reveal a previously unknown regulation mechanism at the co-translational protein level for ethylene homeostasis, in which the NatB-mediated NTA of ACOs render them an intracellular stability to maintain ethylene homeostasis for normal growth and responses.

scholarly journals Thermal Stability Changes in Telomeric G-Quadruplex Structures Due to N6-Methyladenine Modification

Epigenomes ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 5 ◽  
Author(s):  
Ryohei Wada ◽  
Wataru Yoshida
Keyword(s):  
Thermal Stability ◽  
Base Pair ◽  
Genomic Dna ◽  
Biological Functions ◽  
Duplex Structure ◽  
Stacking Interaction ◽  
Hybrid Type ◽  
G Quadruplex ◽  
Melting Analysis ◽  
Thermal Stability Of

N6-methyladenine modification (m6dA) has recently been identified in eukaryote genomic DNA. The methylation destabilizes the duplex structure when the adenine forms a Watson–Crick base pair, whereas the methylation on a terminal unpaired adenine stabilizes the duplex structure by increasing the stacking interaction. In this study, the effects of m6dA modification on the thermal stability of four distinct telomeric G-quadruplex (G4) structures were investigated. The m6dA-modified telomeric oligonucleotide d[AGGG(TTAGGG)3] that forms a basket-type G4 in Na+, d[(TTAGGG)4TT] that forms a hybrid-type G4 in K+ (Form-2), d[AAAGGG(TTAGGG)3AA] that forms a hybrid-type G4 in K+ (Form-1), and d[GGG(TTAGGG)3T] that forms a basket-type G4 with two G-tetrads in K+ (Form-3) were analyzed. Circular dichroism melting analysis demonstrated that (1) A7- and A19-methylation destabilized the basket-type G4 structure that formed in Na+, whereas A13-methylation stabilized the structure; (2) A15-methylation stabilized the Form-2 G4 structure; (3) A15- and A21-methylations stabilized the Form-1 G4 structure; and (4) A12-methylation stabilized the Form-3 G4 structure. These results suggest that m6dA modifications may affect the thermal stability of human telomeric G4 structures in regulating the biological functions.

scholarly journals Staring at the Naked Goddess: Unraveling the Structure and Reactivity of Artemis Endonuclease Interacting with a DNA Double Strand

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3986
Author(s):  
Cécilia Hognon ◽  
Antonio Monari
Keyword(s):  
Dna Cleavage ◽  
Catalytic Mechanism ◽  
Dna Lesions ◽  
Cleavage Reaction ◽  
Dynamic Simulations ◽  
Important Target ◽  
System Adaptation ◽  
Dna Strands ◽  
Dna Strand ◽  
Dna Substrate

Artemis is an endonuclease responsible for breaking hairpin DNA strands during immune system adaptation and maturation as well as the processing of potentially toxic DNA lesions. Thus, Artemis may be an important target in the development of anticancer therapy, both for the sensitization of radiotherapy and for immunotherapy. Despite its importance, its structure has been resolved only recently, and important questions concerning the arrangement of its active center, the interaction with the DNA substrate, and the catalytic mechanism remain unanswered. In this contribution, by performing extensive molecular dynamic simulations, both classically and at the hybrid quantum mechanics/molecular mechanics level, we evidenced the stable interaction modes of Artemis with a model DNA strand. We also analyzed the catalytic cycle providing the free energy profile and key transition states for the DNA cleavage reaction.

Probing nucleus-enriched proteins in single living cells via subcellular-resolved plasmonic immunosandwich assay

The Analyst ◽  
2021 ◽  
Author(s):  
Jia Liu ◽  
Dan Xie ◽  
Zhen Liu
Keyword(s):  
Living Cells ◽  
Nuclear Proteins ◽  
Biological Functions ◽  
Abnormal Expression ◽  
Single Living Cells ◽  
Single Living ◽  
In Cells

Nuclear proteins are crucial in cells and are greatly linked to various biological functions. Abnormal expression of nuclear proteins is associated with many diseases ranging from inflammation to cancer. However,...

scholarly journals Effects on protein synthesis of injecting synthetic polyribonucleotides into living cells

1974 ◽  
Vol 144 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Hugh Woodland ◽  
Sarah E. Ayers
Keyword(s):  
Protein Synthesis ◽  
Xenopus Laevis ◽  
Potent Inhibitor ◽  
Living Cells ◽  
Initiation Factor ◽  
Rna Molecules ◽  
Endogenous Protein ◽  
Limited Supply ◽  
Inhibitor Of Protein Synthesis ◽  
Haemoglobin Synthesis

Micro-injection into the oocytes and eggs of Xenopus laevis was used to ascertain the effects of synthetic polyribonucleotides on protein synthesis in living cells. Poly(U) and poly(A) were not translated detectably, nor did they change the rate of endogenous protein synthesis. The same was true of poly(G,U), poly(A,G,U), poly(A,C,G,U), G-U-G-(U)n, A-(U)n and AUG. In contrast, A-U-G-(U)n was a potent inhibitor of protein synthesis in the cell. This might be because it is initiated normally but lacks a termination codon, or because it inhibits the translation of other molecules in some way not dependent on its normal initiation. Poly(G,U), poly(A,G,U) and poly(A,C,G,U) inhibited haemoglobin synthesis when they were injected into the oocyte with haemoglobin mRNA. The synthetic polyribonucleotides did not inhibit the translation of the natural mRNA when the two sorts of molecules were injected at different times. It is suggested that the synthetic RNA molecules compete with the natural mRNA for a pre-initiation factor in limited supply.

scholarly journals Fragmentation of Plasmid DNA Produced by Gamma Radiation: A Theoretical Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
R. A. S. Silva ◽  
J. D. T. Arruda-Neto ◽  
L. Nieto
Keyword(s):  
Plasmid Dna ◽  
Fragment Size ◽  
Power Laws ◽  
Double Strand Breaks ◽  
Strand Breaks ◽  
Starting Point ◽  
Dna Strands ◽  
High Let ◽  
Fragment Distribution ◽  
Dna Strand

Breaks in DNA, resulting in fragmented parts, can be produced by ionizing radiation which, in turn, is the starting point in the search for novel physical aspects of DNA strands. Double-strand breaks in particular cause disruption of the DNA strand, splitting it into several fragments. In order to study effects produced by radiation in plasmid DNA, a new simple mechanical model for this molecule is proposed. In this model, a Morse-like potential and a high-LET component are used to describe the DNA-radiation interaction. Two power laws, used to fit results of the model, suggest that, firstly, distribution of fragment size is nonextensive and, secondly, that a transition phase is present in the DNA fragment distribution pattern.

scholarly journals Chasing Particularities of Guanine- and Cytosine-Rich DNA Strands

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 434 ◽  
Author(s):  
Marko Trajkovski ◽  
Janez Plavec
Keyword(s):  
Structural Changes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Dna Recombination ◽  
Cd Spectroscopy ◽  
G Quadruplex ◽  
Recombination Processes ◽  
Dna Strands ◽  
Native Polyacrylamide Gel Electrophoresis ◽  
Myc Gene

By substitution of natural nucleotides by their abasic analogs (i.e., 1′,2′-dideoxyribose phosphate residue) at critically chosen positions within 27-bp DNA constructs originating from the first intron of N-myc gene, we hindered hybridization within the guanine- and cytosine-rich central region and followed formation of non-canonical structures. The impeded hybridization between the complementary strands leads to time-dependent structural transformations of guanine-rich strand that are herein characterized with the use of solution-state NMR, CD spectroscopy, and native polyacrylamide gel electrophoresis. Moreover, the DNA structural changes involve transformation of intra- into inter-molecular G-quadruplex structures that are thermodynamically favored. Intriguingly, the transition occurs in the presence of complementary cytosine-rich strands highlighting the inability of Watson–Crick base-pairing to preclude the transformation between G-quadruplex structures that occurs via intertwining mechanism and corroborates a role of G-quadruplex structures in DNA recombination processes.

Sign in / Sign up

Export Citation Format

Share Document