Reaction coupling through interdomain contacts in imidazole glycerol phosphate synthase

The interdomain contacts observed in the crystal structure of S. cerevisiae imidazole glycerol phosphate synthase and a network of amino acids that mediate the [(5'-phosphoribulosyl)-formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (PRFAR) binding signal to the glutaminase active site is analyzed. The amino acids, D359 from the cyclase domain, and K196, a residue adjacent to the glutaminase active site, form the only conserved interdomain salt bridge in the interface region.