DNA Structure Aids Bacterial Survival

Scientists have found that bacterial DNA switches to a more compact form to survive under dry conditions.

AsianScientist (Jun 12, 2014) – A team of scientists from Australia has discovered that bacteria can reshape their DNA to survive dehydration, providing insights into the biological functions of different DNA forms observed in organisms.

A-DNA and B-DNA are two different double helical structures that DNA is known to adopt in organisms. B-DNA is the regular double helix discovered by Watson and Crick and most commonly occurring in organisms, whereas A-DNA is a more compact double helix. Scientists have found that DNA in organisms undergoes the B-A-B transition, during which it changes from B-DNA to A-DNA and back again in response to environmental changes. However, not much is known about the biological function of the transition.

The team from Monash University and the Australian Synchrotron investigated the structure of DNA inside the cells of four live bacterial species. By carefully hydrating and dehydrating the bacteria and then analyzing the cells using an infrared-based technique that detects DNA vibrations, they found that all four species underwent the B-A-B transition.

According to the research, which was published in Journal of the Royal Society Interface, the fact that most of the bacteria remained fully functional after hydration and rehydration suggests that the A-DNA may have played a highly evolved protective role in ensuring the bacteria’s survival under harsh conditions. It also hints at potential links between the B-A-B transition and other conditions threatening survival such as temperature, pH and oxygen levels, and nutrients.

“Our findings may be important in understanding how dormant bacteria that are transferred from dry surfaces may become active and reproduce in the human body,” said co-author Associate Professor Bayden Wood of Monash University.

The article can be found at: Whelan et al. (2014) Detection of an en masse and reversible B- to A-DNA conformational transition in prokaryotes in response to desiccation.

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Source: Monash University; Photo: NIAID/CC/Flickr.
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Alan Aw is a maths enthusiast who likes sharing the fun and beauty of science with others. Besides reading, he enjoys running, badminton, and listening to (and occasionally playing) Bach or Zez Confrey.

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