The folded state of long duplex-DNA chain reflects its solution history.
The higher-order structure of compacted single giant DNA induced by complexation with polypeptide (poly-Arg) in NaCl solution was investigated using fluorescence microscopy. As the poly-Arg concentration increased, the mean size of extended DNA chains gradually decreased. In the presence of excess poly-Arg, individual DNA chains collapsed into compact globules, and the degree of collapse of the DNA chains depended not only on the concentration of poly-Arg, but also on the time course of the addition of poly-Arg and NaCl, indicating that the structure of the collapsed DNA is not determined simply according to the minimum free energy. We discuss theoretically the presence of multiple-stationary states based on a consideration of simple kinetics in the process of binding. Depending on the past history, the number of poly-Arg and Na+ that bind to each DNA changes markedly. This interesting characteristic of long DNA is discussed in relation to the possible mechanism of self-regulation of gene expression in living cells.
Kidoaki
S
S
Graduate School of Human Informatics, Nagoya University, Japan.
Yoshikawa
K
K
D017122:Bacteriophage T4; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008856:Microscopy, Fluorescence; D008962:Models, Theoretical; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D012965:Sodium Chloride; D012996:Solutions
D004279:DNA, Viral; D010455:Peptides; D012996:Solutions; C015462:polyarginine; D012965:Sodium Chloride