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SUMMARY:Sufficient and necessary conditions of entropy driven framework fo
 r hot unfolding of RNA thermometers
DTSTART;VALUE=DATE-TIME:20260922T124500Z
DTEND;VALUE=DATE-TIME:20260922T125000Z
DTSTAMP;VALUE=DATE-TIME:20260914T025327Z
UID:indico-contribution-514@indico.bitp.kiev.ua
DESCRIPTION:Speakers: Oleksiy Kapitanchuk (Bogolyubov Institute for Theore
 tical Physics\, National Academy of Sciences of Ukraine)\nThe exchange of 
 matter and energy between an open system and its surroundings triggers the
 rmally activated spontaneous processes that drive entropy toward a maximum
 . Consequently\, thermal equilibration is fundamentally entropy-driven\, e
 stablishing a final equilibrium state whose population increases with temp
 erature.  In certain cases\, this behavior manifests as an entropy-driven 
 thermal extra-sensitivity. A prime biological example is found in specific
  bacterial mRNAs known as RNA thermometers\, which exhibit an extraordinar
 ily sharp\, temperature-dependent regulation of their translation initiati
 on rate. This regulatory capacity stems from conformational unfolding near
  their ribosome-binding sites. However\, a rigorous thermodynamic derivati
 on of the master equation governing this entropy-driven unfolding has rema
 ined elusive.\nThis report establishes the sufficient and necessary condit
 ions of an entropy-driven framework to model the hot unfolding of RNA ther
 mometers withing a two-configuration approximation. By restricting the sys
 tem to transitions between two primary states (folded and unfolded) a cons
 istent equation for the thermodynamic probability of the entropy-driven un
 folding process is derived. The probability of the unfolded state is deter
 mined and its temperature dependence is mapped. This formulation reveals t
 hat the fundamental necessary condition for an entropy-driven unfolding pr
 ocess is that the entropy of the initial folded state exceeds the entropy 
 of the initial unfolded one\, both calibrated at an initial temperature. W
 ith rising the temperature\, this condition breaks making the unfolding pr
 ocess to be steeply temperature-dependent in a power-like form such that t
 he temperature exponent becomes equal the excess heat capacity at constant
  pressure\, scaled in units of the gas constant. Furthermore\, it is demon
 strated that a high heat capacity increment is driven by an increased numb
 er of degrees of freedom and a growing degeneracy of the unfolded state. T
 he sufficient condition is constituted by explaining the thermal extra-sen
 sitivity of the biomolecules in the framework of entropy-driven scenario\,
  in which the change of enthalpy is considered as minor process\, whereas 
 that of entropy change is regarded prevalent and increasing with temperatu
 re. Finally\, the derived approach shows excellent agreement with existing
  experimental data of melting curves on mRNA unfolding transitions\, thus 
 providing a robust thermodynamic background for RNA thermometry.\n\nThe au
 thors acknowledge the support by the NAS of Ukraine through the project No
 .01261U001252.\n\nhttps://indico.bitp.kiev.ua/event/18/contributions/514/
LOCATION:Bogolyubov Institute for Theoretical Physics Conference Hall
URL:https://indico.bitp.kiev.ua/event/18/contributions/514/
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