Beschreibung:
<jats:p>The hyperthermophilic archaeon<jats:italic>Pyrococcus furiosus</jats:italic>grows by fermenting peptides and carbohydrates to organic acids. In the terminal step, acyl-CoA synthetase (ACS) isoenzymes convert acyl-CoA derivatives to the corresponding acid and conserve energy in the form of ATP. ACS1 and ACS2 were previously purified from<jats:italic>P. furiosus</jats:italic>and have<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mi>α</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>β</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>structures but the genome contains genes encoding three additional<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mi>α</mml:mi></mml:mrow></mml:math>-subunits. The ten possible combinations of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:mi>α</mml:mi></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>genes were expressed in<jats:italic>E. coli</jats:italic>and each resulted in stable and active<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:msub><mml:mrow><mml:mi>α</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>β</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>isoenzymes. The<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M6"><mml:mrow><mml:mi>α</mml:mi></mml:mrow></mml:math>-subunit of each isoenzyme determined CoA-based substrate specificity and between them they accounted for the CoA derivatives of fourteen amino acids. The<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M7"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math>-subunit determined preference for adenine or guanine nucleotides. The GTP-generating isoenzymes are proposed to play a role in gluconeogenesis by producing GTP for GTP-dependent phosphoenolpyruvate carboxykinase and for other GTP-dependent processes. Transcriptional and proteomic data showed that all ten isoenzymes are constitutively expressed indicating that both ATP and GTP are generated from the metabolism of most of the amino acids. A phylogenetic analysis showed that the ACSs of<jats:italic>P. furiosus</jats:italic>and other members of the Thermococcales are evolutionarily distinct from those found throughout the rest of biology, including those of other hyperthermophilic archaea.</jats:p>