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.

Salerno, D., Marrano, C., Cassina, V., Cristofalo, M., Shao, Q., Finzi, L., et al. (2021). Nanomechanics of negatively supercoiled diaminopurine-substituted DNA. NUCLEIC ACIDS RESEARCH, 49(20), 11778-11786 [10.1093/nar/gkab982].

Nanomechanics of negatively supercoiled diaminopurine-substituted DNA

Salerno D.
Co-primo
;
Marrano C. A.
Co-primo
;
Cassina V.;Cristofalo M.;Mantegazza F.
Penultimo
;
2021

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.
Articolo in rivista - Articolo scientifico
2-Aminopurine; DNA, Superhelical; Molecular Dynamics Simulation;
English
2021
49
20
11778
11786
open
Salerno, D., Marrano, C., Cassina, V., Cristofalo, M., Shao, Q., Finzi, L., et al. (2021). Nanomechanics of negatively supercoiled diaminopurine-substituted DNA. NUCLEIC ACIDS RESEARCH, 49(20), 11778-11786 [10.1093/nar/gkab982].
File in questo prodotto:
File Dimensione Formato  
10281-344124_VoR.pdf

accesso aperto

Tipologia di allegato: Publisher’s Version (Version of Record, VoR)
Licenza: Creative Commons
Dimensione 1.64 MB
Formato Adobe PDF
1.64 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/344124
Citazioni
  • Scopus 2
  • ???jsp.display-item.citation.isi??? 1
Social impact