DNA replication is required for the propagation and evolution of living organisms. The mechanism of DNA replication ensures the duplication and transfer of genetic information during cell division. Furthermore, the process needs to be precise, and must occur once and only once per cell cycle. The process is functionally and often structurally conserved in all life forms and can be divided into three phases: initiation, elongation, and termination. DNA replication has been well characterized in bacteria, viruses and bacteriophages, whereas many aspects of the process in eukarya and archaea are still unknown. In particular, the structures and biochemical properties of the proteins and enzymes involved in the initiation process remain to be described. This research will focus on a key enzyme participating in initiation and elongation -- the minichromosome maintenance (MCM) helicase. Various techniques will be employed to determine the structure and biochemical properties of the the MCM helicase from the archaeon Methanothermobacter thermautotrophicus. These studies will contribute significantly to the understanding of DNA replication in archaea. In addition, because the biochemical properties of the archaeal MCM helicase are similar to those of the eukaryotic helicase, the study will also contribute to the understanding of replication in eukarya. Comparison of the results generated in this study with those obtained with MCM helicases from other archaea will provide a richer understanding of the evolution of the replication machinery. Specifically, the study will focus on 1) the determination of the MCM active form and structure, 2) the elucidation of the biochemical properties of the enzyme, and 3) the identification and isolation of proteins that interact with the helicase, and their effect on helicase activity.<br/><br/>Although CARB is a research institution without easy access to students, this project has a long and distinguished history of recruiting students at all levels and providing them with a genuine research experience. The current project will provide training for two graduate students, four high school students (one per project year) and eight undergraduate students (two per project year). There is also direct out reach to the biotechnology program at Montgomery College, the largest and most diverse community college in the Maryland.