Weak interaction induces an ON/OFF switch, whereas strong interaction causes gradual change: folding transition of a long duplex DNA chain by poly-L-lysine.

摘要: A large-scale conformational change in genomic DNA is an essential feature of gene activation living cells. Considerable effort has been applied to explain the mechanism terms key−lock interaction between sequence-specific regulatory proteins and DNA, addition modification histones such as methylation acetylation. However, it still unclear whether these mechanisms can ON/OFF switching a large number genes that accompanies differentiation, carcinogenesis, etc. In this study, using single-molecule observation molecules by fluorescence microscopy with poly-l-lysine different numbers monomer units (n = 3, 5, 9, 92), we found discrete transition higher-order structure long duplex induced short poly-l-lysine, whereas continuous gradual poly-l-lysine. On other hand, polycations lower positive charge have less potential induce compaction. Such a...