Screened DNA packs faster

摘要

Despite being negatively charged, DNA can be compacted to almost crystalline densities inside virus capsids. However, how this is achieved has been debated for years. Most theoretical models predict that attractive DNA-DNA interactions - such as those resulting from the screening effect of nearby positively charged molecules - would facilitate DNA packaging by countering the effects of DNA self-repulsion and loss of entropy. Now, optical-tweezer experiments by Nicholas Keller and colleagues demonstrate that the packaging of DNA is accelerated in the presence of low concentrations of the positively charged polyamine spermidine.