Marked Difference in the Conformational Transition of DNA Caused by Propanol Isomer

Abstract

We measured the changes in the higher-order structure of DNA molecules (λ phage DNA, 48 kbp) at different concentrations of 1- and 2-propanol through single-molecular observation. It is known that 2-propanol is usually adapted for the procedure to isolate genomic DNA from living cells/organs in contrast to 1-propanol. In the present study, it was found that with an increasing concentration of 1-propanol, DNA exhibits reentrant conformational transitions from an elongated coil to a folded globule, and then to an unfolded state. On the other hand, with 2-propanol, DNA exhibits monotonous shrinkage into a compact state. Stretching experiments under direct current (DC) electrical potential revealed that single DNA molecules intermediately shrunk by 1- and 2-propanol exhibit intrachain phase segregation, i.e., coexistence of elongated and compact parts. The characteristic effect of 1-propanol causing the reentrant transition is argued in terms of the generation of water-rich nanoclusters.

Activation/Inhibition of Gene Expression Caused by Alcohols: Relationship with the Viscoelastic Property of a DNA Molecule

“…A comparative study between single DNA observation and CD measurement indicated that the reentrant transition of the secondary structure corresponds to the reentrant transition of the higher-order structure (i.e., coil → compact → coil conformation) [ 3 ]. A similar reentrant transition of the higher-order structure of DNA was also observed with increasing concentrations of 1-propanol above 50% [ 7 ]. However, individual DNA molecules underwent a continuous transition, with gradual shrinking, from an elongated coil into a compact globule with 2-propanol.…”

“…Although it is difficult to ascertain the underlying mechanism of the promotive effect at present, a weak increase in the viscoelasticity of DNA may correlate with transcription and translation efficiency. We recently reported the effect of 1-propanol and 2-propanol on the conformation of DNA based on the single DNA observation and CD measurement [ 7 ]. This study found that the hydrodynamic radius R H of T4 GT7 DNA tends to decrease when alcohol is added.…”