Thermotoga maritima phosphofructokinases: Expression and characterization of two unique enzymes

A pyrophosphate-dependent phosphofructokinase (PPi-PFK) and an ATP-dependen t phosphofructokinase (ATP-PFK) from Thermotoga maritima have been cloned a nd characterized. The PPi-PFK is unique in that the K-m and V-max values in dicate that polyphosphate is the preferred substrate over pyrophosphate; th e enzyme in reality Is a polyphosphate-dependent PFK. The ATP-PFK was not s ignificantly affected by common allosteric effecters (e.g., phosphoenolpyru vate) but was strongly inhibited by PPi and polyphosphate. The results sugg est that the control of the Embden-Meyerhof pathway in this organism is lik ely to be modulated by pyrophosphate and/or polyphosphate.