Marine viruses may contribute to ocean energy

August 30th, 2009 - 3:02 pm ICT by ANI  

Washington, August 30 (ANI): A new study has determined that marine viruses which have borrowed a key set of bacterial photosynthetic genes may be contributing more to the oceans’ energy production than previously thought.Researchers at the Technion-Israel Institute of Technology carried out the study.Technion professor Oded Beja and colleagues suggest that the viruses, or marine phages, may use the genes to gain a competitive advantage over the bacteria they infect and other viruses. But, the findings, along with earlier reports of phages with photosynthetic genes, could “change our calculations of how energy is generated in the oceans,” said Beja. “About 40 percent of photosynthesis on Earth is done in the oceans, and 50 percent of that is done by cyanobacteria. Now we have to ask how much of this is done with viruses,” he added.The transfer of genes from bacteria to viruses is a common mode of evolution among microbes, “like a baton being passed between runners,” said Dr. Paul Falkowski, a professor of marine, earth and planetary sciences at Rutgers University. “Future analyses of the massive sets of genetic data gleaned from marine environments will certainly turn up other genes-beyond those associated with photosynthesis-that have made the leap from microbe to virus,” he said. The genes were found in marine viruses or phages that infect Prochlorococcus and Synechococcus cyanobacteria, the tiny, blue-green and single-celled ocean dwellers that are among the most numerous photosynthetic cells in the seas. The viruses may have incorporated the genes as a way to gain more energy as they infect and reproduce, although the research team hasn’t confirmed whether the genes really do give the viruses an energetic edge. The bacteria genes co-opted by the marine viruses are part of a group, or “cassette” of genes called photosystem I. Photosystem I and another gene cassette called photosystem II genes are essential to the first steps of photosynthesis, absorbing energy from light and transforming into a form that can be used to fuel further reactions in the process.It was a laboratory bet between Beja and Ph.D. students Itai Sharon and Ariella Alperovitch that led to the discovery of the photosystem I cassette in viruses. After scouring genome databases from a selection of marine bacteria and viruses, the students won the bet and found the bacterial photosystem I genes integrated in the viral genome. Clues as to why the photosystem I genes are valuable to the viruses may come from the crystal structure modeling of the photosystem I protein complex from the viruses.The complex’s structure may help the viral complex expand its sources of energy beyond those available to the bacterial complex. “Such an energy boost could be vital to a virus’s fitness,” Beja suggested. (ANI)

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