Research reveals key to world's toughest organism

Oct 19, 2009 By Krishna Ramanujan
D. radiodurans producing nitric oxide (NO) after exposure to UV light. NO is detected by a compound that fluoresces upon reaction with NO.

(PhysOrg.com) -- A new study by Cornell researchers uncovers the details of how the world's toughest bacterium survives lethal radiation exposure.

Listed in the Guinness Book of World Records as "the world's toughest bacterium," Deinococcus radiodurans can withstand extreme temperatures and drought conditions, lack of nutrients and a thousand times more radiation than a human being.

A new study by Cornell researchers reveals that -- a gas molecule used in many metabolic processes in animals and a pollutant in the atmosphere that leads to smog -- plays a key role in D. radiodurans' recovery when exposed to ultraviolet radiation (UV).

The study, appearing online Oct. 19 in the , may have implications for why and how nitric oxides act as signals in mammals for cell-to-cell communication, dilation of the vascular system and activating the immune system; in bacterial responses to antibiotic treatments; and in food safety efforts as D. radiodurans appears in some canned foods. The organism is also studied for use in environmental cleanup of sites contaminated with radiation and toxic chemicals.

Brian Crane, a Cornell associate professor of chemistry and chemical biology, and colleagues, discovered a gene in D. radiodurans that, when exposed to , increases production of an enzyme responsible for creating nitric oxide. They then engineered bacteria without this gene. When zapped by radiation, the engineered bacteria repaired themselves but failed to grow and proliferate.

"Bacteria are much more sensitive to when nitric oxide is not there," said Crane, the paper's senior author. Bhumit Patel, a graduate student in Crane's lab, is the paper's first author. "If you block the nitric oxide signal, the cell will repair but [will] not divide," Crane added.

In addition, the researchers were surprised to find that removing nitric oxide increased sensitivity to radiation but had no effect on the bacteria's ability to withstand other stressors, including exposure to oxidative damage that leads to toxic free radicals.

They also found that under normal circumstances there is a time lag in the process, where induces the cell to repair itself, but it takes a few hours for these bacteria to produce nitric oxide, which then activates a gene involved in cell proliferation and stress responses. "Nitric oxide seems to coordinate this growth response, but it's curious that the bacteria will wait to grow until they have repaired themselves," said Crane. "We don't know why it works this way, but there are analogies in human cells [for other processes]. There may be related pathways for controlling cell growth in animal cells."

Provided by Cornell University (news : web)

Explore further: First detailed picture of a cancer-related cell enzyme in action on a chromosome unit

add to favorites email to friend print save as pdf

Related Stories

Nitric oxide shown to cause colon cancer

Jan 20, 2009

(PhysOrg.com) -- Researchers long ago established a link between inflammation, cancer and the compound nitric oxide, which may be produced when the immune system responds to bacterial infections, including those of the colon. ...

Gas on your mind

Dec 11, 2006

Scientists at the University of Leicester are to gain a greater insight into the workings of the human mind…through the study of a snail’s brain.

Nitric oxide regulates plants as well as people

Apr 28, 2008

Nitric oxide has emerged as an important signaling molecule in plants - as in mammals including people. In studies of a tropical medicinal herb as a model plant, researchers have found that nitric oxide targets a number of ...

Recommended for you

Researchers capture picture of microRNA in action

32 minutes ago

Biologists at The Scripps Research Institute (TSRI) have described the atomic-level workings of "microRNA" molecules, which control the expression of genes in all animals and plants.

Blocking a fork in the road to DNA replication

2 hours ago

A team of Whitehead Institute scientists has discovered the surprising manner in which an enigmatic protein known as SUUR acts to control gene copy number during DNA replication. It's a finding that could shed new light on ...

Cell division, minus the cells

5 hours ago

(Phys.org) —The process of cell division is central to life. The last stage, when two daughter cells split from each other, has fascinated scientists since the dawn of cell biology in the Victorian era. ...

A new method simplifies the analysis of RNA structure

5 hours ago

To understand the function of an RNA molecule, similar to the better-known DNA and vital for cell metabolism, we need to know its three-dimensional structure. Unfortunately, establishing the shape of an RNA ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.