Insights into tRNA-dependent amidotransferase evolution and catalysis from the structure of the Aquifex aeolicus enzyme.

ABSTRACT: Many bacteria form Gln-tRNA(Gln) and Asn-tRNA(Asn) by conversion of the misacylated Glu-tRNA(Gln) and Asp-tRNA(Asn) species catalyzed by the GatCAB amidotransferase in the presence of ATP and an amide donor (glutamine or asparagine). Here, we report the crystal structures of GatCAB from the hyperthermophilic bacterium Aquifex aeolicus, complexed with glutamine, asparagine, aspartate, ADP, or ATP. In contrast to the Staphylococcus aureus GatCAB, the A. aeolicus enzyme formed acyl-enzyme intermediates with either glutamine or asparagine, in line with the equally facile use by the amidotransferase of these amino acids as amide donors in the transamidation reaction. A water-filled ammonia channel is open throughout the length of the A. aeolicus GatCAB from the GatA active site to the synthetas

SUBMITTER: Wu J 

PROVIDER: S-EPMC2830067 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature