Properties of a thermostable 4Fe-ferredoxin from the hyperthermophilic bacterium Thermotoga maritima

A ferredoxin has been purified from one of the most ancient and the most thermophilic bacteria known, Thermotoga maritima, which grous up to 90°C. The reduced protein (Mr approx. 6300) contains a single S = 1 2 [4Fe 4S]1+ cluster with complete cysteinyl ligation, and was unaffected after incubation at 95°C for 12 h. It functioned as an electron carrier for T. maritima pyruvate oxidoreductase. Remarkably, the properties and amino acid sequence of this hyperthermophilic bacterial protein are much more similar to those of ferredoxins from hyperthermophilic archaea, rather than ferredoxins from mesophilic and moderately thermophilic bacteria.