The SV40 viral minichromosome carries a circular double-stranded DNA genome of

PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Biophysics & Medical Physics · Macromolecules, membranes and cell architecture

Forces, Machines and Signals, Ch The elastic polymer: DNA from random walk to worm-like chain

Problem

The SV40 viral minichromosome carries a circular double-stranded DNA genome of 5243 bp5243\,\mathrm{bp}, wrapped as a beads-on-a-string array of nucleosomes with a repeat length of about 167 bp167\,\mathrm{bp} per nucleosome (the extra 20 bp20\,\mathrm{bp} beyond the 147 bp147\,\mathrm{bp} wrapped arc is linker DNA). Assume: base-pair rise 0.34 nm0.34\,\mathrm{nm}; Kuhn length b=100 nmb = 100\,\mathrm{nm}; effective width w≈5 nmw \approx 5\,\mathrm{nm}; and a bending cost of about 65 kBT65\,k_BT per nucleosome, as for the isolated nucleosome example. ((a)) Find NN (Kuhn segments) for the free minichromosome DNA and decide whether swelling matters. ((b)) Estimate the number of nucleosomes needed to wrap the whole genome and the total bending energy this costs, in kBTk_BT and in kJ mol−1\mathrm{kJ\,mol^{-1}} at 298 K298\,\mathrm{K}.

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