Crystal structure of glutamine amidotransferase from Pyrococcus horikoshii OT3

Glutamine amidotransferases (GATases) hydrolyze glutamine and generate ammonia. The glutamine amide nitrogen is utilized for the biosynthesis of a variety of molecules such as amino acids, coenzymes, antibiotics, purine and pyrimidine nucleotides, and glucosamine. Here, we determined the crystal structure of a GATase (PH1346) from the hyperthermophilic archaeon Pyrococcus horikoshii OT3 at 1.89 Å resolution. Its overall structure and active site are the most similar to those of E. coli guanosine 5'-monophosphate (GMP) synthase and Sulfolobus solfataricus anthranilate synthase, respectively. (Communicated by Masanori OTSUKA, M.J.A.)