Unfolding and Targeting Thermodynamics of a DNA Intramolecular Complex with Joined Triplex-Duplex Domains

Sarah E. Johnson, Calliste Reiling-Steffensmeier, Hui Ting Lee, Luis A Marky

Research output: Contribution to journalArticle

Abstract

Our laboratory is interested in developing methods that can be used for the control of gene expression. In this work, we are investigating the reaction of an intramolecular complex containing a triplex-duplex junction with partially complementary strands. We used a combination of isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), and spectroscopy techniques to determine standard thermodynamic profiles for these targeting reactions. Specifically, we have designed single strands to target one loop (CTTTC) or two loops (CTTTC and GCAA) of this complex. Both reactions yielded exothermic enthalpies of -66.3 and -82.8 kcal/mol by ITC, in excellent agreement with the reaction enthalpies of -72.7 and -88.7 kcal/mol, respectively, obtained from DSC Hess cycles. The favorable heat contributions result from the formation of base-pair stacks involving mainly the unpaired bases of the loops. This shows that each complementary strand is able to invade and disrupt the secondary structure. The simultaneous targeting of two loops yielded a more favorable reaction free energy, by approximately -8 kcal/mol, which corresponds to the formation of roughly four base-pair stacks involving the unpaired bases of the 5′-GCAA loop. The main conclusion is that the targeting of loops with a large number of unpaired bases results in a more favorable reaction free energy.

Original languageEnglish (US)
Pages (from-to)1102-1111
Number of pages10
JournalJournal of Physical Chemistry B
Volume122
Issue number3
DOIs
StatePublished - Jan 25 2018

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Calorimetry
Differential Scanning Calorimetry
Titration
Thermodynamics
Base Pairing
Free energy
Differential scanning calorimetry
Enthalpy
DNA
deoxyribonucleic acid
thermodynamics
Exothermic reactions
heat measurement
Gene expression
strands
Spectrum Analysis
Hot Temperature
Spectroscopy
Gene Expression
titration

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Unfolding and Targeting Thermodynamics of a DNA Intramolecular Complex with Joined Triplex-Duplex Domains. / Johnson, Sarah E.; Reiling-Steffensmeier, Calliste; Lee, Hui Ting; Marky, Luis A.

In: Journal of Physical Chemistry B, Vol. 122, No. 3, 25.01.2018, p. 1102-1111.

Research output: Contribution to journalArticle

Johnson, Sarah E. ; Reiling-Steffensmeier, Calliste ; Lee, Hui Ting ; Marky, Luis A. / Unfolding and Targeting Thermodynamics of a DNA Intramolecular Complex with Joined Triplex-Duplex Domains. In: Journal of Physical Chemistry B. 2018 ; Vol. 122, No. 3. pp. 1102-1111.
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