1
|
Sardana D, Alam P, Yadav K, Clovis NS, Kumar P, Sen S. Unusual similarity of DNA solvation dynamics in high-salinity crowding with divalent cations of varying concentrations. Phys Chem Chem Phys 2023; 25:27744-27755. [PMID: 37814577 DOI: 10.1039/d3cp02606j] [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] [Indexed: 10/11/2023]
Abstract
Double-stranded DNA bears the highest linear negative charge density (2e- per base-pair) among all biopolymers, leading to strong interactions with cations and dipolar water, resulting in the formation of a dense 'condensation layer' around DNA. Interactions involving proteins and ligands binding to DNA are primarily governed by strong electrostatic forces. Increased salt concentrations impede such electrostatic interactions - a situation that prevails in oceanic species due to their cytoplasm being enriched with salts. Nevertheless, how these interactions' dynamics are affected in crowded hypersaline environments remains largely unexplored. Here, we employ steady-state and time-resolved fluorescence Stokes shifts (TRFSS) of a DNA-bound ligand (DAPI) to investigate the static and dynamic solvation properties of DNA in the presence of two divalent cations, magnesium (Mg2+), and calcium (Ca2+) at varying high to very-high concentrations of 0.15 M, 1 M and 2 M. We compare the results to those obtained in physiological concentrations (0.15 M) of monovalent Na+ ions. Combining data from fluorescence femtosecond optical gating (FOG) and time-correlated single photon counting (TCSPC) techniques, dynamic fluorescence Stokes shifts in DNA are analysed over a broad range of time-scales, from 100 fs to 10 ns. We find that while divalent cation crowding strongly influences the DNA stability and ligand binding affinity to DNA, the dynamics of DNA solvation remain remarkably similar across a broad range of five decades in time, even in a high-salinity crowded environment with divalent cations, as compared to the physiological concentration of the Na+ ion. Steady-state and time-resolved data of the DNA-groove-bound ligand are seemingly unaffected by ion-crowding in hypersaline solution, possibly due to ions being mostly displaced by the DNA-bound ligand. Furthermore, the dynamic coupling of cations with nearby water may possibly contribute to a net-neutral effect on the overall collective solvation dynamics in DNA, owing to the strong anti-correlation of their electrostatic interaction energy fluctuations. Such dynamic scenarios may persist within the cellular environment of marine life and other biological cells that experience hypersaline conditions.
Collapse
Affiliation(s)
- Deepika Sardana
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Parvez Alam
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Kavita Yadav
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Ndege Simisi Clovis
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Pramod Kumar
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| | - Sobhan Sen
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
| |
Collapse
|
2
|
Gao C, Mohamed HI, Deng J, Umer M, Anwar N, Chen J, Wu Q, Wang Z, He Y. Effects of Molecular Crowding on the Structure, Stability, and Interaction with Ligands of G-quadruplexes. ACS OMEGA 2023; 8:14342-14348. [PMID: 37125118 PMCID: PMC10134454 DOI: 10.1021/acsomega.3c01169] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/03/2023] [Indexed: 05/03/2023]
Abstract
G-quadruplexes (G4s) are widely found in cells and have significant biological functions, which makes them a target for screening antitumor and antiviral drugs. Most of the previous research on G4s has been conducted mainly in diluted solutions. However, cells are filled with organelles and many biomolecules, resulting in a constant state of a crowded molecular environment. The conformation and stability of some G4s were found to change significantly in the molecularly crowded environment, and interactions with ligands were disturbed to some extent. The structure of the G4s and their biological functions are correlated, and the effect of the molecularly crowded environment on G4 conformational transitions and interactions with ligands should be considered in drug design targeting G4s. This review discusses the changes in the conformation and stability of G4s in a physiological environment. Moreover, the mechanism of action of the molecularly crowded environment affecting the G4 has been further reviewed based on previous studies. Furthermore, current challenges and future research directions are put forward. This review has implications for the design of drugs targeting G4s.
Collapse
Affiliation(s)
- Chao Gao
- National
R&D Center for Se-rich Agricultural Products Processing, Hubei
Engineering Research Center for Deep Processing of Green Se-rich Agricultural
Products, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Hany I. Mohamed
- Chemistry
Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Jieya Deng
- National
R&D Center for Se-rich Agricultural Products Processing, Hubei
Engineering Research Center for Deep Processing of Green Se-rich Agricultural
Products, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Muhammad Umer
- Institute
for Forest Resources and Environment of Guizhou and Forestry College,
Research Center of Forest Ecology, Guizhou
University, Guiyang 550025, China
| | - Naureen Anwar
- Department
of Zoology, University of Narowal, Narowal, Punjab 51600, Pakistan
| | - Jixin Chen
- National
R&D Center for Se-rich Agricultural Products Processing, Hubei
Engineering Research Center for Deep Processing of Green Se-rich Agricultural
Products, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Qiao Wu
- Wuhan
Botanical Garden, Chinese Academy of Science, Wuhan 430074, China
| | - Zhangqian Wang
- National
R&D Center for Se-rich Agricultural Products Processing, Hubei
Engineering Research Center for Deep Processing of Green Se-rich Agricultural
Products, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Yi He
- National
R&D Center for Se-rich Agricultural Products Processing, Hubei
Engineering Research Center for Deep Processing of Green Se-rich Agricultural
Products, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| |
Collapse
|
3
|
Simisi Clovis N, Alam P, Kumar Chand A, Sardana D, Firoz Khan M, Sen S. Molecular Crowders Modulate Ligand Binding Affinity to G-Quadruplex DNA by Decelerating Ligand Association. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
4
|
Clovis NS, Sen S. G-Tetrad-Selective Ligand Binding Kinetics in G-Quadruplex DNA Probed with Fluorescence Correlation Spectroscopy. J Phys Chem B 2022; 126:6007-6015. [PMID: 35939531 DOI: 10.1021/acs.jpcb.2c04181] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Probing the kinetics of ligand binding to biomolecules is of paramount interest in biology and pharmacology. Measurements of such kinetic processes provide information on the rate-determining steps that control the binding affinity of ligands to biomolecules, thereby predicting the mechanism of the molecular interaction. In this context, ligand binding to G-quadruplex DNA (GqDNA) structures has attracted tremendous attention primarily because of their use in possible anticancer therapy. Although a large number of G-quadruplex-specific ligands have been proposed, probing the kinetics of G-tetrad-selective binding of (multiple) ligands within a G-quadruplex DNA (GqDNA) structure remains challenging. Most of the earlier studies focused on the thermodynamics of ligand binding; however, the kinetics of ligand association and dissociation with GqDNA, particularly binding of multiple ligands within a GqDNA structure, have not been explored. Here, we propose a simple fluorescence correlation spectroscopy-based method that measures the G-tetrad-selective association and dissociation rates of ligands within a GqDNA structure by correlating the fluorescence fluctuations of a site-specific (5' or 3' end-labeled) fluorophore (Cy3) in GqDNA due to quenching of Cy3 fluorescence, induced by the ligand binding to the G-tetrads. We show that well-known GqDNA ligands, BRACO19, TMPyP4, Hoechst 33258, and Hoechst 33342, have G-tetrad-selective association and dissociation rates, which suggest site-dependent variation of free energy barriers for binding/unbinding of the ligands with GqDNA. We also show that the measured kinetic rates depend not only on the G-tetrad site (5' vs 3' end) but also on the ligand and GqDNA structures.
Collapse
Affiliation(s)
- Ndege Simisi Clovis
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sobhan Sen
- Spectroscopy Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| |
Collapse
|
5
|
New insights into the effect of molecular crowding environment induced by dimethyl sulfoxide on the conformation and stability of G-quadruplex. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.07.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
6
|
Das S, Das S, Singh AK, Datta A. 3-aminoquinoline: a turn-on fluorescent probe for preferential solvation in binary solvent mixtures. Methods Appl Fluoresc 2022; 10. [PMID: 35697038 DOI: 10.1088/2050-6120/ac784d] [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: 04/21/2022] [Accepted: 06/13/2022] [Indexed: 11/11/2022]
Abstract
3-Aminoquinoline (3AQ) has been used as a fluorescent probe for preferential solvation in hexane-ethanol solvent mixtures. Results of the present experiment have been put into context by comparison with prior observations with 5-aminoquinoline (5AQ) as the probe. 3AQ exhibits a relatively small change of dipole moment (Δμ= 2.2 D) upon photoexcitation, compared to 5AQ (Δμ= 6.1D), which might appear to be a hindrance in the way of its use as a solvation probe. Indeed, the values of parameters like spectral shifts are smaller for the present experiment with 3AQ. At the smallest concentration of alcohol used, its local mole fraction around the probe is significantly lower than in the previous experiments with 5AQ. However, these apparent disadvantages are outweighed by the significant increase in fluorescence intensity and lifetime observed with increasing concentration of ethanol in the solvent mixture, as opposed to the drastic fluorescence quenching that occurs for 5AQ. This is a marked advantage in the use of 3AQ in studies like the present one. The local mole fraction of ethanol and preferential solvation index experienced by 3AQ are in line with those reported for 5AQ. The disadvantage of the smaller magnitude of Δμpersists in the time resolved fluorescence experiments, for solvent mixtures with very low ethanol content. Negligible wavelength dependence of fluorescence transients of 3AQ is observed forxp= 0.002,. However, this effect is outweighed at higher alcohol concentrations, for which nanosecond dynamics of preferential solvation is observed.
Collapse
Affiliation(s)
- Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Shirsendu Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Avinash Kumar Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| |
Collapse
|