The research appears in the Nov. 18, 2005 issue of the Journal of Biological Chemistry, in the article "A New Type of Sulfite Reductase, a Novel Coenzyme F420-dependent Enzyme, from the Methanoarchaeon Methanocaldococcus jannaschii".
"The newly discovered enzyme links biological methanogenesis and sulfate reduction, two most ancient respiratory metabolisms, in a unique way," said Mukhopadhyay, whose lab studies organisms that produce methane, in particular M. jannaschii.
Commenting on the research, William Whitman, professor of microbiology at the University of Georgia and an expert in microbial diversity and the evolutionary relationships of prokaryotes, said: "This original work provides important insights into the evolution of the methanogens. These organisms have often been thought to be very limited in their metabolic capabilities. The current study goes a long way to dispelling this simplistic view and greatly extends our knowledge of their versatility."
Methanogenesis is a microbial process in nature that produces methane, an energy resource and a green house gas. Sulfate reduction is also a microbial process where organisms turn sulfate into sulfide, a corrosive compound or gas that smells like rotten eggs.
Methanogenesis is a 2.7?.2-billion-year-old process and sulfate reduction originated at least 3.7 billion years ago on earth. "These two processes apparently cannot exist within one living cell, because the reduction of sulfate produces sulfite as an intermediate, which damages an essential component of the methane production machinery," Mukhopadhyay said. "Consequently, sulfite kills most methanogens."
However, early methanogens must have been able to tolerate su