Use of genome-based microarray analyses to understand the oxidative stress response of an anaerobic microorganism growing at 100°C

Aerobic organisms require molecular O2 for energy conservation. This is a mixed blessing, however, as extremely reactive O2 derivatives (ROS) are produced during normal metabolism that can damage all cellular components. ROS have been implicated in a wide variety of human diseases, including cancer and Alzheimer’s disease, but are also used as a defense system against pathogens and in signal transduction pathways. Aerobes have evolved enzymes such as SOD and catalase to take care of ROS, but such enzymes are typically not found in anaerobic microorganisms. They have a novel response to O2 where the key enzyme is superoxide reductase (SOR). SOR has been characterized from the hyperthermophilic anaerobe, Pyrococcus furiosus by Professor Adams and co-workers . cDNA microarrays will be used to monitor gene expression on a global level to get insight into the complete oxidative response of P. furiosus. Preliminary analyses have shown that SOR and more than a dozen potentially related enzymes are constitutively expressed and are not regulated by various oxidative stresses. This suggests that the organism is continuously ‘armed’ with a response mechanism. However, this is not complete, as in response to a change in redox potential and exposure to organic and ino rganic peroxides, the cell up-regulates the expression of a variety of genes that encode novel proteins. We would like to further examine these effects, as well as the effect of nutrient supply of P. furiosus as some ORFs encoding proteins involved in ami no acid biosynthesis were up-regulated in preliminary experiments. In addition the effect of O2, as well as other oxidants will be studied to get insights into differences of cell permeability as well as oxidant reactivity. Since anaerobic bacteria are a significant threat to humans both in terms of disease and material destruction it is very important to understanding how they respond to oxidative stress since that might lead to new methods to control them.