Rampant helper syndrome: Methane-producing molecule can also repair DNA

Jul 02, 2009

The Archaea are single-celled organisms and a domain unto themselves, quite apart from the so called eukaryotes, being bacteria and higher organisms. Many species live under extreme conditions, and carry out unique biochemical processes shared neither with bacteria nor with eukaryotes. Methanogenic archaeans, for example, can produce methane gas out of carbon dioxide and hydrogen.

The underlying chemical reaction, a reduction, involves the cofactor known as F0 or F420 which is the tiny molecule deazaflavin. It has previously been found only in methanogenic bacteria, and has accordingly been considered the signature molecule for those species. A research group working with Professor Thomas Carell, however, has now shown that this cofactor is also common in eukaryotes, where it performs an entirely different function: deazaflavin is involved in processes. (PNAS Early Edition online, 1 July 2009)

Catalysts assist in chemical reactions without undergoing any alteration of their own. In the cells of living organisms, proteins perform this important function. They carry out the metabolism fundamental to all living processes. Proteins are instrumental in cellular respiration, they for instance reduce oxygen to water and oxidize food into carbon dioxide. This releases the energy that makes life possible at all.

Proteins cannot perform these functions on their own. They depend on small helper molecules. Such molecules are stored inside special pockets in the proteins and carry out essential metabolic functions. The itself produces many of these helpers. Others - like vitamins - must be obtained from food. Severe vitamin deficiencies are a harsh reminder of how essential these are.

Methanogenic bacteria have quite an exceptional task to accomplish: They have to produce methane. In terms of chemistry, this is no mean feat. Methane production is currently one of the most hotly pursued goals for the purposes of renewable energy. It is also a serious greenhouse gas.

Enzymatic methane production involves the tiny molecule deazaflavin, known as cofactor F0 or cofactor F420. This cofactor is stored inside special proteins of methanogenic bacteria, and is essential for methane biosynthesis. Cofactor F0/F420 is a small molecule that, until now, has only been found in methanogenic bacteria. It is regarded as the signature molecule for such species.

"We have now shown that this picture is not entirely true," Carell says. "This cofactor is significantly more widespread in the biosphere than previously assumed. Most importantly, it also occurs in higher organisms, the so-called eukaryotes. But in these, it performs a completely different task." As the researchers were able to demonstrate, the cofactor is involved in DNA repair processes. Specifically, repair of UV damage to the DNA molecule.

Plants and many other organisms that are exposed to intense sunlight must cope with an enormous degree of damage to their genes. To repair those mutations, they need the help of complex enzymes. These photolyases in turn require cofactor FAD - aka vitamin B2 - to accomplish this function. It has long been suspected that these crucial enzymes require yet another cofactor to provide the energy that DNA repair requires.

"We have now shown that, in many organisms, this cofactor is F0/F420," Carell reports. "This molecule has been conclusively detected in DNA repair enzymes of Drosophila melanogaster, the fruit fly. Not long ago, another research group even postulated that F0/F420 is co-responsible for DNA repair in plants. Our view of cofactor F420 as a signature molecule for methanogenic species has therefore radically changed: this cofactor is widespread and it is essential for both methane synthesis and for DNA repair."

Source: Ludwig-Maximilians-Universität München

Explore further: Ocean microbes display remarkable genetic diversity

add to favorites email to friend print save as pdf

Related Stories

Scientists take 'snapshots' of enzyme action

Jun 13, 2006

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory, the New York Structural Biology Center, and SGX Pharmaceuticals, Inc., have determined the atomic crystal structure and functional ...

MIT biologists solve vitamin puzzle

Mar 21, 2007

Solving a mystery that has puzzled scientists for decades, MIT and Harvard researchers have discovered the final piece of the synthesis pathway of vitamin B12-the only vitamin synthesized exclusively by microorganisms.

Sequencing the Genome of a New Kind of Methane Producer

Aug 03, 2006

About 10 to 25 percent of the world's methane emissions come from flooded rice paddies. Methane is a greenhouse gas produced by various groups of microorganisms (methanogenic Archaea). Oxygen is usually highly ...

Experimental TB drug explodes bacteria from the inside out

Nov 27, 2008

An international team of biochemists has discovered how an experimental drug unleashes its destructive force inside the bacteria that cause tuberculosis (TB). The finding could help scientists develop ways to treat dormant ...

Paired microbes eliminate methane using sulfur pathway

Jan 17, 2008

Anaerobic microbes in the Earth's oceans consume 90 percent of the methane produced by methane hydrates – methane trapped in ice – preventing large amounts of methane from reaching the atmosphere. Researchers now have ...

Real-time observation of the DNA-repair mechanism

May 22, 2008

For the first time, researchers at Delft University of Technology have witnessed the spontaneous repair of damage to DNA molecules in real time. They observed this at the level of a single DNA molecule. Insight into this ...

Recommended for you

Ocean microbes display remarkable genetic diversity

2 hours ago

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...

Cell resiliency surprises scientists

3 hours ago

New research shows that cells are more resilient in taking care of their DNA than scientists originally thought. Even when missing critical components, cells can adapt and make copies of their DNA in an alternative ...

Cell division speed influences gene architecture

Apr 23, 2014

Speed-reading is a technique used to read quickly. It involves visual searching for clues to meaning and skipping non-essential words and/ or sentences. Similarly to humans, biological systems are sometimes ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

ArtyNouveau
not rated yet Jul 02, 2009
"...so called eukaryotes, being bacteria and higher organisms."

Bacteria are not eukaryotes.

See: http://www.biolog...ain.html

More news stories

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.

Ocean microbes display remarkable genetic diversity

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...

Study links California drought to global warming

While researchers have sometimes connected weather extremes to man-made global warming, usually it is not done in real time. Now a study is asserting a link between climate change and both the intensifying California drought ...

Autism Genome Project delivers genetic discovery

A new study from investigators with the Autism Genome Project, the world's largest research project on identifying genes associated with risk for autism, has found that the comprehensive use of copy number variant (CNV) genetic ...