Balanced branching in transcription termination

The theory of stochastic transcription termination based on free-energy competition [von Hippel. P. H. & Yager. T, D, (1992) Science 255, 809-812 and von Hippel. P. H. & Yager, T. D, (1991) Proc. Natl. Acad. Sci. USA 88, 2307-2311] requires two or more reaction rates to be delicately balanced over a wide range of physical conditions. A large body of work on glasses and large molecules suggests that this balancing should be impossible in such a large system in the absence of a new organizing principle of matter. We review the experimental literature of termination and find no evidence for such a principle, but do find many troubling inconsistencies. most notably, anomalous memory effects. These effects suggest that termination has a deterministic component and may conceivably not be stochastic at all. We find that a key experiment by Wilson and von Hippel [Wilson, K. S. & von Hippel. P. H, (1994) J. Moi. Biol, 244, 36-51] thought to demonstrate stochastic termination was an incorrectly analyzed regulatory effect of Mg2+ binding.