Antarctic yields new enzyme with uses for cloning

Press, 19 September 1985, Page 14

Antarctic yields new enzyme with uses for cloning

Scientists experimenting with microscopic organisms living in tiny brine channels in sea ice and in the sub-freezing oceans surrounding Antarctica have isolated a new type of enzyme useful in gene synthesis and cloning, the National Science Foundation reports. The scientists say the enzyme is “50 times more potent” in its action than that now used in genetic engineering laboratories. Enzymes are proteins formed in plants, animals and bacteria that act as catalysts in starting or speeding specific chemical reactions. They usually become inactive or unstable at temperatures outside the normal range for this organism. The finding was made by a team from the University of Southern California investigating the importance of algae and bacteria that live in the Antarctic sea ice. The team headed by Dr Cornelius W. Sullivan, director of marine biology research at USC, reported its results to NSF, which finances, and manages all United States activity in Antarctica. During expeditions to McMurdo Sound, and to the Weddell Sea, on the opposite side of the. continent, the scientists found large concentrations of these ice-dwelling organisms that provide a food source for crustaceans and krill. Dr Sullivan and his colleague

also discovered that a group of bacteria living in the sea ice can grow rapidly in their permanently cold environment. “This suggests that metabolism of the bacteria is remarkably adapted to the environment and that bacterial machinery is very efficient at sub-zero temperatures for synthesis of macromolecules such as DNA, RNA, proteins, carbohydrates, and lipids,” Dr Sullivan told NSF. DNA (deoxyribonucleic acid) is the material that carries the genetic information used in the construction of living cells; RNA (riboncleic acid), is the material that controls protein production in cells. Dr Sullivan and USC molecular biologists, Drs Hiroaki Shizuya and Hiromi Kobori have taken advantage of certain adaptations of these organisms to their extreme environment to learn how bacteria can be useful to man. “We have found that these unusual bacteria produce biochemical substances that potentially have important roles in the development of biotechnology,” Dr Sullivan said. Alkaline phosphatase (APase) is an enzyme that removes certain groups of phosphate from RNA and DNA, an essential step for gene synthesis and cloning. An APase isolated from the bacterium Escherichia coli (E.coli) is currently used in laboratories conducting genetic engineering experiments. The disadvantage of E.coli APase is that it is extremely heat-resist-

ant, therefore impossible to inactivate by simple heat treatment. It is now inactivated in laboratories by an elaborate procedure. “We have isolated a new type of APase from the Antarctic Ocean bacteria and have completed purification of the new enzyme,” Dr Sullivan said. “We found that the new enzyme is 50 times more potent in its action that E.coli APase and that the enzyme can easily be inactivated by heating.” In addition to the APase, bacteria from Antarctica may provide sources for identifying and isolating new types of useful enzymes that are catalytically efficient to zero degrees Centigrade or that are able to be inactivated at moderate temperatures, Dr Sullivan said. These bacteria may also be important sources of new antibiotics since they have not previously been examined for antibiotic production.” Another finding by the USC biologists was that Antarctic bacteria often carry an extrachromosmal element called plasmids, suggesting that plasmids are übiquitous in natural microbial populations in the pristine marine ecosystem of Antarctica. Their finding, they said, may provide vital information to marine ecologists interested in examining the functions and evolution of plasmids in natural environments which are essentially free from man-made contaminants.