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Ghoneim M, Musselman CA. Single-Molecule Characterization of Cy3.5 -Cy5.5 Dye Pair for FRET Studies of Nucleic Acids and Nucleosomes. J Fluoresc 2023; 33:413-421. [PMID: 36435903 PMCID: PMC9957830 DOI: 10.1007/s10895-022-03093-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Single molecule FRET (Forster resonance energy transfer) is very powerful method for studying biomolecular binding dynamics and conformational transitions. Only a few donor - acceptor dye pairs have been characterized for use in single-molecule FRET (smFRET) studies. Hence, introducing and characterizing additional FRET dye pairs is important in order to widen the scope of applications of single-molecule FRET in biomolecular studies. Here we characterize the properties of the Cy3.5 and Cy5.5 dye pair under FRET at the single-molecule level using naked double-stranded DNA (dsDNA) and the nucleosome. We show that this pair of dyes is photostable for ~ 5 min under continuous illumination. We also report Cy3.5-Cy5.5 FRET proximity dependence and stability in the presence of several biochemical buffers and photoprotective reagents in the context of double-stranded DNA. Finally, we demonstrate compatibility of the Cy3.5-Cy5.5 pair for smFRET in vitro studies of nucleosomes.
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Affiliation(s)
- Mohamed Ghoneim
- Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, 80045, Aurora, CO, USA.
| | - Catherine A. Musselman
- grid.430503.10000 0001 0703 675XBiochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, 80045 Aurora, CO USA
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Brehove M, Shatoff E, Donovan BT, Jipa CM, Bundschuh R, Poirier MG. DNA sequence influences hexasome orientation to regulate DNA accessibility. Nucleic Acids Res 2019; 47:5617-5633. [PMID: 31216039 PMCID: PMC6582347 DOI: 10.1093/nar/gkz283] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/03/2019] [Accepted: 04/20/2019] [Indexed: 02/02/2023] Open
Abstract
Nucleosomes, the fundamental organizing units of eukaryotic genomes, contain ∼146 base pairs of DNA wrapped around a histone H3–H4 tetramer and two histone H2A–H2B dimers. Converting nucleosomes into hexasomes by removal of a H2A–H2B dimer is an important regulatory event, but its regulation and functional consequences are not well-understood. To investigate the influence of hexasomes on DNA accessibility, we used the property of the Widom-601 Nucleosome Positioning Sequence (NPS) to form homogeneously oriented hexasomes in vitro. We find that DNA accessibility to transcription factors (TF) on the hexasome H2A–H2B distal side is identical to naked DNA, while the accessibility on the H2A–H2B proximal side is reduced by 2-fold, which is due to a 2-fold reduction in hexasome unwrapping probability. We then determined that a 23 bp region of the Widom-601 NPS is responsible for forming homogeneously oriented hexasomes. Analysis of published ChIP-exo data of hexasome containing genes identified two DNA sequence motifs that correlate with hexasome orientation in vivo, while ExoIII mapping studies of these sequences revealed they generate homogeneously oriented hexasomes in vitro. These results indicate that hexasome orientation, which is influenced by the underlying DNA sequence in vivo, is important for modulating DNA accessibility to regulate transcription.
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Affiliation(s)
- Matthew Brehove
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Elan Shatoff
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Benjamin T Donovan
- Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA
| | - Caroline M Jipa
- Department of Physics, Ohio State University, Columbus, OH 43210, USA
| | - Ralf Bundschuh
- Department of Physics, Ohio State University, Columbus, OH 43210, USA.,Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA.,Division of Hematology, Ohio State University, Columbus, OH 43210, USA.,Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
| | - Michael G Poirier
- Department of Physics, Ohio State University, Columbus, OH 43210, USA.,Biophysics Graduate Program, Ohio State University, Columbus, OH 43210, USA.,Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA.,Ohio State Biochemistry Program, Ohio State University, Columbus, OH 43210, USA
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Donovan BT, Huynh A, Ball DA, Patel HP, Poirier MG, Larson DR, Ferguson ML, Lenstra TL. Live-cell imaging reveals the interplay between transcription factors, nucleosomes, and bursting. EMBO J 2019; 38:embj.2018100809. [PMID: 31101674 DOI: 10.15252/embj.2018100809] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 04/12/2019] [Accepted: 04/25/2019] [Indexed: 12/19/2022] Open
Abstract
Transcription factors show rapid and reversible binding to chromatin in living cells, and transcription occurs in sporadic bursts, but how these phenomena are related is unknown. Using a combination of in vitro and in vivo single-molecule imaging approaches, we directly correlated binding of the Gal4 transcription factor with the transcriptional bursting kinetics of the Gal4 target genes GAL3 and GAL10 in living yeast cells. We find that Gal4 dwell time sets the transcriptional burst size. Gal4 dwell time depends on the affinity of the binding site and is reduced by orders of magnitude by nucleosomes. Using a novel imaging platform called orbital tracking, we simultaneously tracked transcription factor binding and transcription at one locus, revealing the timing and correlation between Gal4 binding and transcription. Collectively, our data support a model in which multiple RNA polymerases initiate transcription during one burst as long as the transcription factor is bound to DNA, and bursts terminate upon transcription factor dissociation.
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Affiliation(s)
- Benjamin T Donovan
- Biophysics Graduate Program, The Ohio State University, Columbus, OH, USA
| | - Anh Huynh
- Department of Physics, Boise State University, Boise, ID, USA
| | - David A Ball
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Heta P Patel
- Division of Gene Regulation, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Michael G Poirier
- Biophysics Graduate Program, The Ohio State University, Columbus, OH, USA.,Departments of Physics, Chemistry & Biochemistry, Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Matthew L Ferguson
- Department of Physics, Boise State University, Boise, ID, USA .,Biomolecular Sciences, Boise State University, Boise, ID, USA
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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