SCIENCE AT THE SHINE DOME canberra 7 - 9 may 2008

New Fellows Seminar

Wednesday, 7 May 2008

Professor Murray Badger
Research School of Biological Sciences, Australian National University

Murray Badger has a degree in agricultural science from Sydney University, graduating with the University Medal. He has a PhD from the Australian National University (ANU) on the biochemistry of the photosynthetic CO₂ fixing enzyme Rubisco. His first postdoctoral appointment was at the Carnegie Institution of Washington, Department of Plant Biology, at Stanford University in California. He returned to the ANU on a QEII Fellowship and has remained there, being appointed to professor in 1998. His research has centred on understanding CO₂ fixation in plants, algae and cyanobacteria considering aspects of molecular biology, physiological function and evolution. His awards have included the Goldacre Medal from the Australian Society of Plant Scientists and he is listed as one of Australia’s most highly cited plant and animal scientists.

Turbo-charged photosynthesis: adapting to an atmosphere with low CO₂ and high oxygen

Some 2.5 billion years ago the most significant change to life on Earth occurred – the evolution of the oxygen-producing photosynthesis reaction in cyanobacteria (blue-green algae). This caused dramatic changes in atmospheric oxygen and carbon dioxide (CO₂) levels, leading to today’s relatively high oxygen and low CO₂ conditions. These changes demanded the development of strategies by photosynthetic organisms to help the CO₂ fixing enzyme, Rubisco, to capture declining CO₂. Two different approaches have been used to solve this problem: either evolve a better Rubisco enzyme or develop an active CO₂ concentrating mechanism to turbo-charge an imperfect enzyme. I have studied the concentrating mechanism in cyanobacteria and helped to discover that it is based on the integrated operation of a suite of proteins that actively accumulate bicarbonate in the cell. Bicarbonate is converted to CO₂ in a compartment where Rubisco is force-fed CO₂. Knowledge of the genes involved in this process from over 40 different cyanobacteria is enabling us to see how different bicarbonate transporters and Rubisco compartments may allow adaptation to different environments.