000186471 001__ 186471
000186471 005__ 20181203023127.0
000186471 0247_ $$2doi$$a10.1103/PhysRevLett.110.148105
000186471 022__ $$a0031-9007
000186471 02470 $$2ISI$$a000317190800019
000186471 037__ $$aARTICLE
000186471 245__ $$aThermodynamics of Writhe in DNA Minicircles from Molecular Dynamics Simulations
000186471 260__ $$aCollege Pk$$bAmer Physical Soc$$c2013
000186471 269__ $$a2013
000186471 300__ $$a5
000186471 336__ $$aJournal Articles
000186471 520__ $$aDNA supercoiling plays a role in genetic control by imposing torsional stress. This can induce writhe, which changes the global shape of the DNA. We have used atomistic molecular dynamics simulations to partition the free energy changes driving the writhing and unwrithing transitions in supercoiled minicircle DNA. The calculations show that while writhing is energetically driven, the unwrithing transition occurs because the circular state has a higher configurational entropy than the plectoneme. Writhing improves the van der Waals interactions between stacked bases, but can be suppressed by electrostatic repulsion within the negatively charged backbone strands in low salt conditions where electrostatic screening is poor. The free energy difference between circular and plectonemic DNA is determined by such a delicate balance of opposing thermodynamic terms that any perturbation in the environment, such as a change in salt concentration, can be sufficient to convert between these two states. This switchable behavior provides a mechanism for supercoiled DNA to store and communicate biological information physically as well as chemically. DOI: 10.1103/PhysRevLett.110.148105
000186471 700__ $$0245218$$aMitchell, Jonathan S.$$g209403$$uEcole Polytech Fed Lausanne, Sect Math, CH-1015 Lausanne, Switzerland
000186471 700__ $$aHarris, Sarah A.$$uUniv Leeds, Sch Phys & Astron, Leeds LS2 9JT, W Yorkshire, England
000186471 773__ $$j110$$k14$$tPhysical Review Letters
000186471 909C0 $$0252346$$pLCVMM$$xU10163
000186471 909CO $$ooai:infoscience.tind.io:186471$$pSB$$particle
000186471 937__ $$aEPFL-ARTICLE-186471
000186471 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000186471 980__ $$aARTICLE