Localization of DNA damage by current exchanging repair enzymes: effects of cooperativity on detection time

Abstract

How DNA repair enzymes find the relatively rare sites of damage is not known in great detail. Recent experiments and molecular data suggest that the individual repair enzymes do not work independently of each other, but rather interact with each other through currents exchanged along DNA. A damaged site in DNA hinders this exchange and this makes it possible to quickly free up resources from error free stretches of DNA. Here the size of the speedup gained from this current exchange mechanism is calculated and the characteristic length and time scales are identified. In particular for Escherichia coli we estimate the speedup to be 50000/N, where N is the number of repair enzymes participating in the current exchange mechanism. Even though N is not exactly known a speedup of order 10 is not entirely unreasonable. Furthermore upon over expression of repair enzymes the detection time only varies as one over the squareroot of N and not as 1/N. This behavior is of interest in assessing the impact of stress full and radioactive environments on individual cell mutation rates.