Nucleoside Triphosphate Pyrophosphohydrolase (EC 188.8.131.52) MazG-like domain found in Escherichia coli phosphoribosyl-ATP pyrophosphohydrolase (HisIE or PRATP-PH) and its homologs
This family includes Escherichia coli phosphoribosyl-ATP pyrophosphohydrolase, HisIE, and its homologs from all three kingdoms of life. E. coli HisIE is encoded by the hisIE gene, which is formed by hisE gene fused to hisl. HisIE is a bifunctional enzyme responsible for the second and third steps of the histidine-biosynthesis pathway. Its N-terminal and C-terminal domains have phosphoribosyl-AMP cyclohydrolase (HisI) and phosphoribosyl-ATP pyrophosphohydrolase (HisE or PRATP-PH) activity, respectively. This family corresponds to the C-terminal domain of HisIE and includes many hisE gene encoding proteins, all of which show significant sequence similarity to Mycobacterium tuberculosis phosphoribosyl-ATP pyrophosphohydrolase (HisE or PRATP-PH). These proteins may be responsible for only the second step in the histidine-biosynthetic pathway, irreversibly hydrolyzing phosphoribosyl-ATP (PRATP) to phosphoribosyl-AMP (PRAMP) and pyrophosphate.