1
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Genthon A, Dvirnas A, Ambjörnsson T. Equilibrium melting probabilities of a DNA molecule with a defect: An exact solution of the Poland-Scheraga model. J Chem Phys 2023; 159:145102. [PMID: 37815110 DOI: 10.1063/5.0168915] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/20/2023] [Indexed: 10/11/2023] Open
Abstract
In this study we derive analytically the equilibrium melting probabilities for basepairs of a DNA molecule with a defect site. We assume that the defect is characterized by a change in the Watson-Crick basepair energy of the defect basepair, and in the associated two stacking energies for the defect, as compared to the remaining parts of the DNA. The defect site could, for instance, occur due to DNA basepair mismatching, cross-linking, or by the chemical modifications when attaching fluorescent labels, such as fluorescent-quencher pairs, to DNA. Our exact solution of the Poland-Scheraga model for DNA melting provides the probability that the labeled basepair, and its neighbors, are open at different temperatures. Our work is of direct importance, for instance, for studies where fluorophore-quencher pairs are used for studying single basepair fluctuations of designed DNA molecules.
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Affiliation(s)
- Arthur Genthon
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
| | - Albertas Dvirnas
- Computational Biology and Biological Physics, Centre for Environmental and Climate Science, Lund University, SE-223 62 Lund, Sweden
| | - Tobias Ambjörnsson
- Computational Biology and Biological Physics, Centre for Environmental and Climate Science, Lund University, SE-223 62 Lund, Sweden
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2
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Chang Y, Zeng X, Peng S, Lai R, Yang M, Wang D, Zhou X, Shao Y. All-or-None Selectivity in Probing Polarity-Determined Trinucleotide Repeat Foldings with a Parity Resolution by a Beyond-Size-Matching Ligand. Anal Chem 2023; 95:3746-3753. [PMID: 36745842 DOI: 10.1021/acs.analchem.2c04810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Abnormal amplification of trinucleotide repeats (TNRs) is associated with neurodegenerative diseases by forming a particular hairpin bulge. It is well known that the polarity and parity of TNRs can regulate the formed hairpin structures. Therefore, there is a great challenge to efficiently discriminate the hairpin structures of TNRs with substantial selectivity. Herein, we developed a fluorescent ligand of pseudohypericin (Pse) with a beyond-size-matching (BSM) geometry to selectively sense hairpin structures of GTC and CTG TNRs. The GTC hairpin structures can bind with Pse dominantly at extreme T-T mismatches by the virtue of their most extrahelical conformations, while there is no binding event to occur with the polarity-inverted counterpart CTG hairpin structures because of the limited space provided by their intrahelical T-T mismatches. In addition, this all-or-none response with the polarity-dependent folding (PoDF) is independent of the length of these TNRs. Interestingly, the parity-dependent folding (PaDF) of GTC hairpin structures can also be resolved. Besides pure TNRs, the competency of this BSM ligand to sense the PoDF and PaDF effects was also generalized to DNAs with TNRs occurring at loop and stem end regions. To our knowledge, this is the first experimental observation with the state-of-the-art performance over the fluorescence measurement of PoDF and PaDF in TNRs. Our work provides an expedient way to elucidate the TNR folding by designing ligands having BSM features.
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Affiliation(s)
- Yun Chang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Xingli Zeng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Shuzhen Peng
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Rong Lai
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Mujing Yang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Dandan Wang
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Xiaoshun Zhou
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
| | - Yong Shao
- Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China
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3
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Wang SD, Zhang RB, Eriksson LA. Markov state models elucidate the stability of DNA influenced by the chiral 5S-Tg base. Nucleic Acids Res 2022; 50:9072-9082. [PMID: 35979954 PMCID: PMC9458442 DOI: 10.1093/nar/gkac691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/15/2022] [Accepted: 07/30/2022] [Indexed: 12/24/2022] Open
Abstract
The static and dynamic structures of DNA duplexes affected by 5S-Tg (Tg, Thymine glycol) epimers were studied using MD simulations and Markov State Models (MSMs) analysis. The results show that the 5S,6S-Tg base caused little perturbation to the helix, and the base-flipping barrier was determined to be 4.4 kcal mol-1 through the use of enhanced sampling meta-eABF calculations, comparable to 5.4 kcal mol-1 of the corresponding thymine flipping. Two conformations with the different hydrogen bond structures between 5S,6R-Tg and A19 were identified in several independent MD trajectories. The 5S,6R-Tg:O6HO6•••N1:A19 hydrogen bond is present in the high-energy conformation displaying a clear helical distortion, and near barrier-free Tg base flipping. The low-energy conformation always maintains Watson-Crick base pairing between 5S,6R-Tg and A19, and 5S-Tg base flipping is accompanied by a small barrier of ca. 2.0 KBT (T = 298 K). The same conformations are observed in the MSMs analysis. Moreover, the transition path and metastable structures of the damaged base flipping are for the first time verified through MSMs analysis. The data clearly show that the epimers have completely different influence on the stability of the DNA duplex, thus implying different enzymatic mechanisms for DNA repair.
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Affiliation(s)
- Shu-dong Wang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, South Street No. 5, Zhongguancun, Haidan District, 100081 Beijing, China
| | - Ru-bo Zhang
- Correspondence may also be addressed to Ru-bo Zhang.
| | - Leif A Eriksson
- To whom correspondence should be addressed. Tel: +46 31 786 9117;
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4
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Fakharzadeh A, Zhang J, Roland C, Sagui C. Novel eGZ-motif formed by regularly extruded guanine bases in a left-handed Z-DNA helix as a major motif behind CGG trinucleotide repeats. Nucleic Acids Res 2022; 50:4860-4876. [PMID: 35536254 PMCID: PMC9122592 DOI: 10.1093/nar/gkac339] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/19/2022] [Accepted: 05/05/2022] [Indexed: 12/19/2022] Open
Abstract
The expansion of d(CGG) trinucleotide repeats (TRs) lies behind several important neurodegenerative diseases. Atypical DNA secondary structures have been shown to trigger TR expansion: their characterization is important for a molecular understanding of TR disease. CD spectroscopy experiments in the last decade have unequivocally demonstrated that CGG runs adopt a left-handed Z-DNA conformation, whose features remain uncertain because it entails accommodating GG mismatches. In order to find this missing motif, we have carried out molecular dynamics (MD) simulations to explore all the possible Z-DNA helices that potentially form after the transition from B- to Z-DNA. Such helices combine either CpG or GpC Watson-Crick steps in Z-DNA form with GG-mismatch conformations set as either intrahelical or extrahelical; and participating in BZ or ZZ junctions or in alternately extruded conformations. Characterization of the stability and structural features (especially overall left-handedness, higher-temperature and steered MD simulations) identified two novel Z-DNA helices: the most stable one displays alternately extruded Gs, and is followed by a helix with symmetrically extruded ZZ junctions. The G-extrusion favors a seamless stacking of the Watson-Crick base pairs; extruded Gs favor syn conformations and display hydrogen-bonding and stacking interactions. Such conformations could have the potential to hijack the MMR complex, thus triggering further expansion.
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Affiliation(s)
- Ashkan Fakharzadeh
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Jiahui Zhang
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Christopher Roland
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
| | - Celeste Sagui
- Department of Physics, North Carolina State University, Raleigh, NC 27695-8202, USA
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5
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Abstract
![]()
We
explore the process of base-flipping for four central bases,
adenine, guanine, cytosine, and thymine, in a deoxyribonucleic acid
(DNA) duplex using the energy landscape perspective. NMR imino-proton
exchange and fluorescence correlation spectroscopy studies have been
used in previous experiments to obtain lifetimes for bases in paired
and extrahelical states. However, the difference of almost 4 orders
of magnitude in the base-flipping rates obtained by the two methods
implies that they are exploring different pathways and possibly different
open states. Our results support the previous suggestion that minor
groove opening may be favored by distortions in the DNA backbone and
reveal links between sequence effects and the direction of opening,
i.e., whether the base flips toward the major or the minor groove
side. In particular, base flipping along the minor groove pathway
was found to align toward the 5′ side of the backbone. We find
that bases align toward the 3′ side of the backbone when flipping
along the major groove pathway. However, in some cases for cytosine
and thymine, the base flipping along the major groove pathway also
aligns toward the 5′ side. The sequence effect may be caused
by the polar interactions between the flipping-base and its neighboring
bases on either of the strands. For guanine flipping toward the minor
groove side, we find that the equilibrium constant for opening is
large compared to flipping via the major groove. We find that the
estimated rates of base opening, and hence the lifetimes of the closed
state, obtained for thymine flipping through small and large angles
along the major groove differ by 6 orders of magnitude, whereas for
thymine flipping through small angles along the minor groove and large
angles along the major groove, the rates differ by 3 orders of magnitude.
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Affiliation(s)
- Nicy
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K
| | - Debayan Chakraborty
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - David J. Wales
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, U.K
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6
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Selectively recognizing extrahelical conformations of DNA trinucleotide repeats by a hydroxylated porphyrin ligand. Anal Chim Acta 2022; 1190:339265. [PMID: 34857129 DOI: 10.1016/j.aca.2021.339265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 10/06/2021] [Accepted: 11/08/2021] [Indexed: 11/24/2022]
Abstract
Trinucleotide repeats (TRs) with abnormal lengths and atypical folding are implicated in various neurodegenerative diseases. The least stable cytosine-cytosine (C-C) mismatches in TRs when structuring into homoduplexes/hairpins have more chance in certain sequence contexts to preferentially adopt an extrahelical (E-motif) conformation with respect to those in polarity-inverted intrahelical counterparts. Herein, we designed a trihydroxyphenyl porphyrin ligand (POH3) to meet the challenge towards resolving the E-motif conformation. POH3 exhibited a specific 2:1 binding with DNAs adopting the E-motif cytosine conformation, independent of the TRs length. The trihydroxyl pattern was very crucial to gain the E-motif selectivity over the polarity-inverted counterparts via the complementary hydrogen bonding that occurred in the minor groove. Our work first elucidates the rationale in designing ligands to selectively resolve the E-motif nucleotides within TRs.
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7
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Wang SD, Eriksson LA, Zhang RB. Dynamics of 5R-Tg Base Flipping in DNA Duplexes Based on Simulations─Agreement with Experiments and Beyond. J Chem Inf Model 2022; 62:386-398. [PMID: 34994562 PMCID: PMC8790752 DOI: 10.1021/acs.jcim.1c01169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Damaged or mismatched
DNA bases are normally thought to be able
to flip out of the helical stack, providing enzymes with access to
the faulty genetic information otherwise hidden inside the helix.
Thymine glycol (Tg) is one of the most common products of nucleic
acid damage. However, the static and dynamic structures of DNA duplexes
affected by 5R-Tg epimers are still not clearly understood, including
the ability of these to undergo spontaneous base flipping. Structural
effects of the 5R-Tg epimers on the duplex DNA are herein studied
using molecular dynamics together with reliable DFT based calculations.
In comparison with the corresponding intact DNA, the cis-5R,6S-Tg epimer base causes little perturbation to the duplex DNA,
and a barrier of 4.9 kcal mol–1 is obtained by meta-eABF
for cis-5R,6S-Tg base flipping out of the duplex
DNA, comparable to the 5.4 kcal mol–1 obtained for
the corresponding thymine flipping in intact DNA. For the trans-5R,6R-Tg epimer, three stable local structures were
identified, of which the most stable disrupts the Watson–Crick
hydrogen-bonded G5/C20 base pair, leading to conformational distortion
of the duplex. Interestingly, the relative barrier height of the 5R-Tg
flipping is only 1.0 kcal mol–1 for one of these trans-5R,6R-Tg epimers. Water bridge interactions were identified
to be essential for 5R-Tg flipping. The study clearly demonstrates
the occurrence of partial trans-5R,6R-Tg epimer flipping
in solution.
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Affiliation(s)
- Shu Dong Wang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, South Street no 5, Zhongguancun, Haidian District, 100081 Beijing, China
| | - Leif A Eriksson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9c, 405 30 Göteborg, Sweden
| | - Ru Bo Zhang
- School of Chemistry and Chemical Engineering, Beijing Institute of Technology, South Street no 5, Zhongguancun, Haidian District, 100081 Beijing, China
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8
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Dayanidhi PD, Vaidyanathan VG. Understanding the ancillary ligand effect on luminescent cyclometalated Ir(III) complex as a reporter for 2-acetylaminofluorene DNA(AAF-dG) adduct. J Biol Inorg Chem 2021; 27:189-199. [PMID: 34843001 DOI: 10.1007/s00775-021-01920-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/17/2021] [Indexed: 11/26/2022]
Abstract
Mutagenic agents such as aromatic amines undergo metabolic activation and produce DNA adducts at C8 position of guanine bases. N-2-acetylaminofluorene (AAF) generates different mutational outcomes when placed at G1, G2, and G3 of a NarI sequence (-G1G2CG3CC/T-). These outcomes are dictated by the conformations adopted by these adducts. Detection of such lesions is of considerable interest owing to their hazardous effects. Here, we report the synthesis of three cyclometalated [Ir(L)2dppz]+ complexes (L = 2-phenylpyridine (ppy) 1; benzo[h]quinoline (bhq) 2; 2-phenylquinoline (pq) 3; dppz = dipyrido[3,2-a:2',3'-c]phenazine) and their interaction with AAF adducted NarI DNA. Remarkably, complexes 1 and 2 displayed dominant 3LC transition characteristic of polar environment despite binding to the adducted sites. On the other hand, complex 3 binds to NarI sequences and behaves as a luminescent reporter for AAF-modified DNA. The results reported here emphasize that molecular light switching phenomenon can be stimulated by switching ancillary ligands and might act as potential probes for covalent-DNA defects.
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Affiliation(s)
- P David Dayanidhi
- Advanced Materials Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai, 600020, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - V G Vaidyanathan
- Advanced Materials Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai, 600020, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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9
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Khamari L, Pramanik S, Shekhar S, Mahato P, Mukherjee S. Preferential Binding of Epirubicin Hydrochloride with Single Nucleotide Mismatched DNA and Subsequent Sequestration by a Mixed Micelle. J Phys Chem B 2021; 125:11660-11672. [PMID: 34652157 DOI: 10.1021/acs.jpcb.1c06944] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Targeting mismatched base pairs containing DNA using small molecules and exploring the underlying mechanism involved during the binding interactions is one of the fundamental aspects of drug design. These molecules in turn are used in nucleic acid targeted therapeutics and cancer diagnosis. In this work, we systematically delineate the binding of the anticancer drug, epirubicin hydrochloride (EPR) with 20-mer duplex DNA, having both natural nucleobase pairing and thermodynamically least stable non-Watson-Crick base pairing. From the thermal denaturation studies, we observed that EPR can remarkably enhance the thermal stability of cytosine-cytosine (CC) and cytosine-thymine (CT) mismatched (MM) DNA over other 20-mer duplex DNA. From steady-state fluorescence spectroscopy and isothermal titration calorimetry studies, we concluded that EPR binds strongly with the mismatched duplex DNA through the intercalation binding mode. The interaction of EPR and duplex DNA has also been monitored at a single molecular resolution using fluorescence correlation spectroscopy (FCS). Dynamic quantitates such as diffusion coefficients and hydrodynamic radii obtained from an FCS study along with association and dissociation rate constants estimated from intensity time trace analyses further substantiate the stronger binding affinity of EPR to the thermally less stable mismatched DNA, formed by the most discriminating nucleobase (viz. cytosine). Additionally, we have shown that EPR can be sequestered from nucleic acids using a mixed micellar system of an anionic surfactant and a triblock copolymer. From thermal denaturation studies and circular dichroism spectroscopy, we found that the extent of drug sequestration depends on the binding affinity of EPR to the duplex DNA, and this mixed micellar system can be employed for the removal of excess drug in the case of a drug overdose.
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Affiliation(s)
- Laxmikanta Khamari
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Srikrishna Pramanik
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Shashi Shekhar
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Paritosh Mahato
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Saptarshi Mukherjee
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
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10
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Levintov L, Paul S, Vashisth H. Reaction Coordinate and Thermodynamics of Base Flipping in RNA. J Chem Theory Comput 2021; 17:1914-1921. [PMID: 33594886 DOI: 10.1021/acs.jctc.0c01199] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Base flipping is a key biophysical event involved in recognition of various ligands by ribonucleic acid (RNA) molecules. However, the mechanism of base flipping in RNA remains poorly understood, in part due to the lack of atomistic details on complex rearrangements in neighboring bases. In this work, we applied transition path sampling (TPS) methods to study base flipping in a double-stranded RNA (dsRNA) molecule that is known to interact with RNA-editing enzymes through this mechanism. We obtained an ensemble of 1000 transition trajectories to describe the base-flipping process. We used the likelihood maximization method to determine the refined reaction coordinate (RC) consisting of two collective variables (CVs), a distance and a dihedral angle between nucleotides that form stacking interactions with the flipping base. The free energy profile projected along the refined RC revealed three minima, two corresponding to the initial and final states and one for a metastable state. We suggest that the metastable state likely represents a wobbled conformation of nucleobases observed in NMR studies that is often characterized as the flipped state. The analyses of reactive trajectories further revealed that the base flipping is coupled to a global conformational change in a stem-loop of dsRNA.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, United States
| | - Sanjib Paul
- Department of Chemistry, New York University, New York 10003, New York, United States
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham 03824, New Hampshire, United States
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11
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Iqbal MJ, Li Z, Khan MA, Zhu Y, Hussain W, Su H, Qiu QM, Shoukat R, Li H. Studies on the structure and chirality of A-motif in adenosine monophosphate nucleotide metal coordination complexes. CrystEngComm 2021. [DOI: 10.1039/d1ce00276g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Structure and chirality of A-motif.
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Affiliation(s)
- Muhammad Javed Iqbal
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Zhongkui Li
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Maroof Ahmad Khan
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Yanhong Zhu
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Wajid Hussain
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Hao Su
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Qi-Ming Qiu
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Rizwan Shoukat
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
| | - Hui Li
- Key Laboratory of Cluster Science of Ministry of Education
- School of Chemistry and Chemical Engineering
- Beijing Institute of Technology
- Beijing 100081
- P. R. China
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12
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Desai PR, Brahmachari S, Marko JF, Das S, Neuman KC. Coarse-grained modelling of DNA plectoneme pinning in the presence of base-pair mismatches. Nucleic Acids Res 2020; 48:10713-10725. [PMID: 33045724 DOI: 10.1093/nar/gkaa836] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 09/14/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022] Open
Abstract
Damaged or mismatched DNA bases result in the formation of physical defects in double-stranded DNA. In vivo, defects in DNA must be rapidly and efficiently repaired to maintain cellular function and integrity. Defects can also alter the mechanical response of DNA to bending and twisting constraints, both of which are important in defining the mechanics of DNA supercoiling. Here, we use coarse-grained molecular dynamics (MD) simulation and supporting statistical-mechanical theory to study the effect of mismatched base pairs on DNA supercoiling. Our simulations show that plectoneme pinning at the mismatch site is deterministic under conditions of relatively high force (>2 pN) and high salt concentration (>0.5 M NaCl). Under physiologically relevant conditions of lower force (0.3 pN) and lower salt concentration (0.2 M NaCl), we find that plectoneme pinning becomes probabilistic and the pinning probability increases with the mismatch size. These findings are in line with experimental observations. The simulation framework, validated with experimental results and supported by the theoretical predictions, provides a way to study the effect of defects on DNA supercoiling and the dynamics of supercoiling in molecular detail.
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Affiliation(s)
- Parth Rakesh Desai
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA.,Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | - John F Marko
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA.,Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
| | - Keir C Neuman
- Laboratory of Single Molecule Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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13
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Bouchal T, Durník I, Illík V, Réblová K, Kulhánek P. Importance of base-pair opening for mismatch recognition. Nucleic Acids Res 2020; 48:11322-11334. [PMID: 33080020 PMCID: PMC7672436 DOI: 10.1093/nar/gkaa896] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 09/09/2020] [Accepted: 09/30/2020] [Indexed: 01/04/2023] Open
Abstract
Mismatch repair is a highly conserved cellular pathway responsible for repairing mismatched dsDNA. Errors are detected by the MutS enzyme, which most likely senses altered mechanical property of damaged dsDNA rather than a specific molecular pattern. While the curved shape of dsDNA in crystallographic MutS/DNA structures suggests the role of DNA bending, the theoretical support is not fully convincing. Here, we present a computational study focused on a base-pair opening into the minor groove, a specific base-pair motion observed upon interaction with MutS. Propensities for the opening were evaluated in terms of two base-pair parameters: Opening and Shear. We tested all possible base pairs in anti/anti, anti/syn and syn/anti orientations and found clear discrimination between mismatches and canonical base-pairs only for the opening into the minor groove. Besides, the discrimination gap was also confirmed in hotspot and coldspot sequences, indicating that the opening could play a more significant role in the mismatch recognition than previously recognized. Our findings can be helpful for a better understanding of sequence-dependent mutability. Further, detailed structural characterization of mismatches can serve for designing anti-cancer drugs targeting mismatched base pairs.
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Affiliation(s)
- Tomáš Bouchal
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Ivo Durník
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Viktor Illík
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Kamila Réblová
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Petr Kulhánek
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
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14
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Sobek J, Schlapbach R. Dependence of Fluorescence Quenching of CY3 Oligonucleotide Conjugates on the Oxidation Potential of the Stacking Base Pair. Molecules 2020; 25:molecules25225369. [PMID: 33212871 PMCID: PMC7698394 DOI: 10.3390/molecules25225369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/15/2020] [Accepted: 11/16/2020] [Indexed: 01/02/2023] Open
Abstract
To understand the complex fluorescence properties of astraphloxin (CY3)-labelled oligonucleotides, it is necessary to take into account the redox properties of the nucleobases. In oligonucleotide hybrids, we observed a dependence of the fluorescence intensity on the oxidation potential of the neighbouring base pair. For the series I < A < G < 8-oxoG, the extent of fluorescence quenching follows the trend of decreasing oxidation potentials. In a series of 7 nt hybrids, stacking interactions of CY3 with perfect match and mismatch base pairs were found to stabilise the hybrid by 7–8 kJ/mol. The fluorescence measurements can be explained by complex formation resulting in fluorescence quenching that prevails over the steric effect of a reduced excited state trans-cis isomerisation, which was expected to increase the fluorescence efficiency of the dye when stacking to a base pair. This can be explained by the fact that, in a double strand, base pairing and stacking cause a dramatic change in the oxidation potential of the nucleobases. In single-molecule fluorescence measurements, the oxidation of G to 8-oxoG was observed as a result of photoinduced electron transfer and subsequent chemical reactions. Our results demonstrate that covalently linked CY3 is a potent oxidant towards dsDNA. Sulfonated derivatives should be used instead.
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15
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Bangalore DM, Heil HS, Mehringer CF, Hirsch L, Hemmen K, Heinze KG, Tessmer I. Automated AFM analysis of DNA bending reveals initial lesion sensing strategies of DNA glycosylases. Sci Rep 2020; 10:15484. [PMID: 32968112 PMCID: PMC7511397 DOI: 10.1038/s41598-020-72102-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 08/25/2020] [Indexed: 12/31/2022] Open
Abstract
Base excision repair is the dominant DNA repair pathway of chemical modifications such as deamination, oxidation, or alkylation of DNA bases, which endanger genome integrity due to their high mutagenic potential. Detection and excision of these base lesions is achieved by DNA glycosylases. To investigate the remarkably high efficiency in target site search and recognition by these enzymes, we applied single molecule atomic force microscopy (AFM) imaging to a range of glycosylases with structurally different target lesions. Using a novel, automated, unbiased, high-throughput analysis approach, we were able to resolve subtly different conformational states of these glycosylases during DNA lesion search. Our results lend support to a model of enhanced lesion search efficiency through initial lesion detection based on altered mechanical properties at lesions. Furthermore, its enhanced sensitivity and easy applicability also to other systems recommend our novel analysis tool for investigations of diverse, fundamental biological interactions.
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Affiliation(s)
- Disha M Bangalore
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Hannah S Heil
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Christian F Mehringer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Lisa Hirsch
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Katherina Hemmen
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany
| | - Katrin G Heinze
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany.
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080, Würzburg, Germany.
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