title: Molecular and biochemical characterization of bifunctional pyruvate decarboxylases and pyruvate ferredoxin oxidoreductases from Thermotoga maritima and Thermotoga hypogea.
abstract: Hyperthermophilic bacteria Thermotoga maritima and Thermotoga hypogea produce ethanol as a metabolic end product, which is resulted from acetaldehyde reduction catalysed by an alcohol dehydrogenase (ADH). However, the enzyme that is involved in the production of acetaldehyde from pyruvate is not well characterized. An oxygen sensitive and coenzyme A-dependent pyruvate decarboxylase (PDC) activity was found to be present in cell free extracts of T. maritima and T. hypogea. Both enzymes were purified and found to have pyruvate ferredoxin oxidoreductase (POR) activity, indicating their bifunctionality. Both PDC and POR activities from each of the purified enzymes were characterized in regards to their optimal assay conditions including pH dependency, oxygen sensitivity, thermal stability, temperature dependency and kinetic parameters. The close relatedness of the PORs that was shown by sequence analysis could be an indication of the presence of such bifunctionality in other hyperthermophilic bacteria. This is the first report of a bifunctional PDC/POR enzyme in hyperthermophilic bacteria. The PDC and the previously reported ADHs are most likely the key enzymes catalysing the production of ethanol from pyruvate in bacterial hyperthermophiles.
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and.
authors.forename: Mohammad S
authors.initials: MS
authors.lastname: Eram
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and.
authors.forename: Alton
authors.initials: A
authors.lastname: Wong
authors.affiliation: Department of Chemistry and Physics, Roger Williams University, One Old Ferry Road, Bristol, RI 02809, USA.
authors.forename: Erica
authors.initials: E
authors.lastname: Oduaran
authors.affiliation: Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and kma@uwaterloo.ca.
authors.forename: Kesen
authors.initials: K
authors.lastname: Ma
mesh_terms: D000079:Acetaldehyde / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D004795:Enzyme Stability; D000431:Ethanol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D064251:Multifunctional Enzymes / Q000737:chemistry* / Q000302:isolation & purification; D011767:Pyruvate Decarboxylase / Q000737:chemistry* / Q000302:isolation & purification; D050743:Pyruvate Synthase / Q000737:chemistry* / Q000302:isolation & purification; D019289:Pyruvic Acid / Q000378:metabolism; D013696:Temperature; D020124:Thermotoga maritima / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D064251:Multifunctional Enzymes; D000431:Ethanol; D019289:Pyruvic Acid; D050743:Pyruvate Synthase; D011767:Pyruvate Decarboxylase; D000079:Acetaldehyde
keywords: Thermotoga hypogea; Thermotoga maritime; hyperthermophiles; pyruvate decarboxylase; pyruvate ferredoxin oxidoreductase