ATP sulfurylase from the hyperthermophilic chemolithotroph Aquifex aeolicus is a bacterial ortholog of the enzyme from filamentous fungi. (The subunit contains an adenosine 5′-phosphosulfate (APS) kinase-like, C-terminal domain.) The enzyme is highly heat stable with a half-life > 1 h at 90°C. Steady-state kinetics are consistent with a random A-B, ordered P-Q mechanism where A = MgATP, B = SO2- 4, P = PPi, and Q = APS. The kinetic constants suggest that the enzyme is optimized to act in the direction of ATP + sulfate formation. Chlorate is competitive with sulfate and with APS. In sulfur chemolithotrophs, ATP sulfurylase provides an efficient route for recycling PPi produced by biosynthetic reactions. However, the protein possesses low APS kinase activity. Consequently, it may also function to produce PAPS for sulfate ester formation or sulfate assimilation when hydrogen serves as the energy source and a reduced inorganic sulfur source is unavailable.
- Adenylylsulfate (APS) kinase, from Aquifex aeolicus, hyperthermophile, ATP sulfurylase from
- ATP sulfurylase, from Aquifex aeolicus
- Chemolithotroph, ATP sulfurylase, and APS kinase in
- Sulfurylase, from a hyperthermophilic bacterium
ASJC Scopus subject areas
- Molecular Biology