Abstract :
DNAs in bacteria are usually circular and supercoiled in the manner of a twisted telephone cord. Supercoil dynamics, in addition to usual Zimm relaxation, include a long relaxation time corresponding to the ‘slithering’ of DNA sequence around inside the supercoil; this is believed to be important in brining distant DNA sequences together in bacterial cells. Simple ‘repton’ models of slithering are proposed and numerically investigated for unbranched and branched supercoils. The first passage time by slithering for two distant sites on a N-monomer molecule with no branches is found to be N3, as for conventional reptation. Allowing supercoil branching and branch motion, effects expected for large DNAs, reduces this time to N2.
