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Ann. N.Y. Acad. Sci., Annals PrePrint, published online ahead of print December 20, 2007 doi: 10.1196/annals.1419.001 Copyright © 2007 by the New York Academy of Sciences description
1 Biochemistry, Virginia Tech, Blacksburg, Virginia, United States 2 Biochemistry, Virginia Tech, Rm 103 Engel Hall (0308), Blacksburg, Virginia, 24061, United States
* To whom correspondence should be addressed. E-mail: rhwhite{at}vt.edu. PrePrint Abstract
The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not—the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen sensitive reactions and cofactors to function in the new oxygen containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extrapolation to those metabolic pathways occurring in the last universal common ancestor (LUCA). In this chapter we will review some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii. Key Words:
archaea, central metabolism, purine biosynthesis, pyrimidine biosynthesis, amino acid biosynthesis, carbohydrate metabolism, isoprenoid biosynthesis, archaeal lipids
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