Hydrogenase of the Hyperthermophile Pyrococcus furiosus is an Elemental Sulfur Reductase or Sulfhydrogenase: Evidence for a Sulfur-Reducing Hydrogenase Ancestor

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 90; no. 11; pp. 5341 - 5344
• Main Authors: Ma, Kesen, Schicho, Richard N., Kelly, Robert M., Michael W. W. Adams
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01-06-1993; National Acad Sciences; National Academy of Sciences
• Subjects: 550200 - Biochemistry; 550500 - Metabolism; Analytical, structural and metabolic biochemistry; Archaea; Archaea - enzymology; BACTERIA; BASIC BIOLOGICAL SCIENCES; BIOCHEMISTRY; Biological and medical sciences; Biological Evolution; Cellular biology; CHEMISTRY; Chromatography; Chromatography, Ion Exchange; Chromatography, Liquid; Durapatite; Electrons; ELEMENTS; ENZYMES; Enzymes and enzyme inhibitors; Evolution; Fundamental and applied biological sciences. Psychology; GROWTH; Hot Temperature; Hydrogen-Ion Concentration; Hydrogenase - isolation & purification; Hydrogenase - metabolism; HYDROGENASES; Hydroxyapatites; Kinetics; Marine; METABOLISM; METALLOPROTEINS; MICROORGANISMS; NONMETALS; ORGANIC COMPOUNDS; OXIDOREDUCTASES; Oxidoreductases - isolation & purification; Oxidoreductases - metabolism; Polysulfides; PROTEINS; Protons; Pyrococcus furiosus; RUBREDOXIN; Rubredoxins; SEAS; Species Specificity; SULFATE-REDUCING BACTERIA; Sulfides; SULFUR; SURFACE WATERS; THERMAL WATERS; VENTS; Hydrogenase; Purification; Enzymatic activity; Enzyme; Archaeobacteria; Bacteria; Evolution; Thermophily
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.11.5341

Microorganisms growing near and above 100⚬C have recently been discovered near shallow and deep sea hydrothermal vents. Most are obligately dependent upon the reduction of elemental sulfur (S0) to hydrogen sulfide (H2S) for optimal growth, even though S0reduction readily occurs abiotically at their growth temperatures. The sulfur reductase activity of the anaerobic archaeon Pyrococcus furiosus, which grows optimally at 100⚬C by a metabolism that produces H2S if S0is present, was found in the cytoplasm. It was purified anaerobically and was shown to be identical to the hydrogenase that had been previously purified from this organism. Both S0and polysulfide served as substrates for H2S production, and the S0reduction activity but not the H2-oxidation activity was enhanced by the redox protein rubredoxin. The H2-oxidizing and S0-reduction activities of the enzyme also showed different responses to pH, temperature, and inhibitors. This bifunctional "sulfhydrogenase" enzyme can, therefore, dispose of the excess reductant generated during fermentation using either protons or polysulfides as the electron acceptor. In addition, purified hydrogenases from both hyperthermophilic and mesophilic representatives of the archaeal and bacterial domains were shown to reduce S0to H2S. It is suggested that the function of some form of ancestral hydrogenase was S0reduction rather than, or in addition to, the reduction of protons.