Archaea Genomes - HALOARCULA MARISMORTUI

Haloarcula marismortui is a Halophilic microorganism that thrives in extreme saline environments such as the Dead Sea.

In 2000 the complete genome sequence of Halobacterium NRC-1, another archaeal organism, which, like H. marismortui, proliferates in saturating salt solutions. With both genomes available for comparison scientists will be able to more fully understand the molecular and genetic mechanisms of behavioural differences among closely related species inhabiting an extreme environment.

Both Halobacterium NRC-1 and H. marismortui dominate highly saline environments that experience frequent fluctuations in a variety of environmental factors including those that cause severe DNA damage. These microorganisms have learned, through millions of years of evolution, efficient ways to negotiate these constant stress conditions. For example, both of these archaea have a high degree of negatively charged amino acids on the surface of their folded proteins. This unusual property enables these proteins to withstand high salinity in the cytoplasm (required to counterbalance external salinity) which otherwise causes most proteins to collapse and lose function

The study revealed that both of these organisms shared a common ancestor millions of years ago and through the course of evolution Halobacterium NRC-1 appears to have shed nearly half of its genes, perhaps to streamline its life cycle.

References:

http://www.separationsnow.com/basehtml/SepH/1,1353,6-1-1-0-0-news_detail-0-1717,00.html