Numerous members of the third kingdom, Archaea, are extreme hyperthermophiles, able to grow at temperatures up to 113 degrees C in some cases. Many of these microorganisms have small genomes, on the order of 2 million base pairs, and are from the deeper branches of the phylogenetic tree, in agreement with the notion that the most ancient ancestral microorganisms grew at high temperatures. They pose interesting fundamental questions in molecular biology, since all of their life processes occur at elevated temperatures. For instance, how can the DNA replicate with high fidelity, and how do these organisms avoid excessive mutation due to heat-induced DNA lesions, and what repair systems do they have? How do regulatory proteins recognize and bind to operators at temperatures above 100 degrees C? How does the chromosome remain stable? How are proteins able to function at such high temperatures? What new strategies for these and other cellular processes will be uncovered as we increase our study of extreme hyperthermophiles? Dr. Miller proposes to develop a functional genomic analysis of one of these organisms, Pyrobaculum aerophilum, an Archaeon that can grow at 103 C, and to compare aspects of the functional genome with other high temperature microorganisms. He has, in collaboration with Dr. Mel Simon's laboratory at CalTech, completed the sequence of the entire 2.2 megabase genome of Pyrobaculum aerophilum. He will use this sequence, which he is in the process of annotating, as a starting point for genomic studies of this microorganism. He will employ genome wide in vitro analyses of gene expression, and will develop a genetic system to permit additional methods of analysis to be used. The investigator will also begin some comparative studies on the genome of Pyrolobus fumarii, which can grow at 113 C, the highest known temperature for any living organism.
