Aspartate Transcarbamylase from the Hyperthermophilic Eubacterium Thermotoga maritima: Fused Catalytic and Regulatory Polypeptides Form an Allosteric Enzyme

In the allosteric aspartate transcarbamylase (ATCase) from the hyperthermophilic eubacterium Thermotoga maritima, the catalytic and regulatory functions, which in class B ATCases are carried out by specialized polypeptides, are combined on a single type of polypeptide assembled in trimers. The ATCases from T. maritima and Treponema denticola present intriguing similarities, suggesting horizontal gene transfer.