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Salerno D, Marrano CA, Cassina V, Cristofalo M, Shao Q, Finzi L, Mantegazza F, Dunlap D. Nanomechanics of negatively supercoiled diaminopurine-substituted DNA. Nucleic Acids Res 2021; 49:11778-11786. [PMID: 34718727 PMCID: PMC8599871 DOI: 10.1093/nar/gkab982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 10/05/2021] [Accepted: 10/13/2021] [Indexed: 11/25/2022] Open
Abstract
Single molecule experiments have demonstrated a progressive transition from a B- to an L-form helix as DNA is gently stretched and progressively unwound. The particular sequence of a DNA segment defines both base stacking and hydrogen bonding that affect the partitioning and conformations of the two phases. Naturally or artificially modified bases alter H-bonds and base stacking and DNA with diaminopurine (DAP) replacing adenine was synthesized to produce linear fragments with triply hydrogen-bonded DAP:T base pairs. Both unmodified and DAP-substituted DNA transitioned from a B- to an L-helix under physiological conditions of mild tension and unwinding. This transition avoids writhing and the ease of this transition may prevent cumbersome topological rearrangements in genomic DNA that would require topoisomerase activity to resolve. L-DNA displayed about tenfold lower persistence length than B-DNA. However, left-handed DAP-substituted DNA was twice as stiff as unmodified L-DNA. Unmodified DNA and DAP-substituted DNA have very distinct mechanical characteristics at physiological levels of negative supercoiling and tension.
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Affiliation(s)
- Domenico Salerno
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via R. Follereau 3, Vedano al Lambro (MB), Italy
| | - Claudia Adriana Marrano
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via R. Follereau 3, Vedano al Lambro (MB), Italy
| | - Valeria Cassina
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via R. Follereau 3, Vedano al Lambro (MB), Italy
| | - Matteo Cristofalo
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via R. Follereau 3, Vedano al Lambro (MB), Italy
| | - Qing Shao
- Department of Physics, Emory University, Atlanta, GA USA
| | - Laura Finzi
- Department of Physics, Emory University, Atlanta, GA USA
| | - Francesco Mantegazza
- School of Medicine and Surgery, BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via R. Follereau 3, Vedano al Lambro (MB), Italy
| | - David Dunlap
- Department of Physics, Emory University, Atlanta, GA USA
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Du QS, Chen D, Xie NZ, Huang RB, Chou KC. Insight into a molecular interaction force supporting peptide backbones and its implication to protein loops and folding. J Biomol Struct Dyn 2015; 33:1957-72. [PMID: 25375237 PMCID: PMC4536944 DOI: 10.1080/07391102.2014.984333] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/02/2014] [Indexed: 11/20/2022]
Abstract
Although not being classified as the most fundamental protein structural elements like α-helices and β-strands, the loop segment may play considerable roles for protein stability, flexibility, and dynamic activity. Meanwhile, the protein loop is also quite elusive; i.e. its interactions with the other parts of protein as well as its own shape-maintaining forces have still remained as a puzzle or at least not quite clear yet. Here, we report a molecular force, the so-called polar hydrogen-π interaction (Hp-π), which may play an important role in supporting the backbones of protein loops. By conducting the potential energy surface scanning calculations on the quasi π-plane of peptide bond unit, we have observed the following intriguing phenomena: (1) when the polar hydrogen atom of a peptide unit is perpendicularly pointing to the π-plane of other peptide bond units, a remarkable Hp-π interaction occurs; (2) the interaction is distance and orientation dependent, acting in a broad space, and belonging to the 'point-to-plane' one. The molecular force reported here may provide useful interaction concepts and insights into better understanding the loop's unique stability and flexibility feature, as well as the driving force of the protein global folding.
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Affiliation(s)
- Qi-Shi Du
- State Key Laboratory of Non-food Biomass and Enzyme Technology, National Engineering Research Center for Non-food Biorefinery, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi530007, China
- Nanning Fermentation and Enzyme Engineering Research Center, Life Science and Biotechnology College, Guangxi University, Nanning, Guangxi530004, China
- Gordon Life Science Institute, 53 South Cottage Road, Belmont, MA02478, USA
| | - Dong Chen
- State Key Laboratory of Non-food Biomass and Enzyme Technology, National Engineering Research Center for Non-food Biorefinery, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi530007, China
- Nanning Fermentation and Enzyme Engineering Research Center, Life Science and Biotechnology College, Guangxi University, Nanning, Guangxi530004, China
| | - Neng-Zhong Xie
- State Key Laboratory of Non-food Biomass and Enzyme Technology, National Engineering Research Center for Non-food Biorefinery, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi530007, China
| | - Ri-Bo Huang
- State Key Laboratory of Non-food Biomass and Enzyme Technology, National Engineering Research Center for Non-food Biorefinery, Guangxi Academy of Sciences, 98 Daling Road, Nanning, Guangxi530007, China
- Nanning Fermentation and Enzyme Engineering Research Center, Life Science and Biotechnology College, Guangxi University, Nanning, Guangxi530004, China
| | - Kuo-Chen Chou
- Center of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, Jeddah21589, Saudi Arabia
- Gordon Life Science Institute, 53 South Cottage Road, Belmont, MA02478, USA
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Zoli M. Twist versus nonlinear stacking in short DNA molecules. J Theor Biol 2014; 354:95-104. [DOI: 10.1016/j.jtbi.2014.03.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 03/02/2014] [Accepted: 03/19/2014] [Indexed: 10/25/2022]
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