Metabolic and Enzymological Studies of Sulfur-Dependent Marine Hyperthermophiles

摘要

The results from this study have provided the first insights into howhyperthermophilic organisms obtain energy from the metabolism of C and N compounds, and how this can be achieved at high temperatures. These organisms have unusual pathways based on the rarely-used element tungsten (W), which is present in the novel enzymes AOR, FOR and GAPOR. We propose that W is much more suited to catalyze low potential reactions (such as those catalyzed by GAPOR, AOR and FOR) at extreme temperatures, and that such reactions could not be catalyzed by Mo-containing enzymes. We have cloned and sequenced the first genes for any W-protein, and the first genes for hyperthermophilic oxidoreductases. In addition, a new pathway for peptide metabolism as been proposed, again involving new types of enzyme, such as VOR, IOR and ACS. We also provided the first definitive model for the evolution of mesophilic oxidoreductases from hyperthermophilic enzymes, and the first crystal structure for a hyperthermophilic enzyme (AOR) was obtained, providing the first insights in to protein stability at extreme temperatures.