Mutagenesis identifies a conserved tyrosine residue important for the activity of uroporphyrinogen III synthase from Anacystis nidulans.

Uroporphyrinogen III synthase from the cyanobacterium Anacystis nidulans was overproduced in Escherichia coli and analyzed by site specific mutagenesis. Of the nine conserved amino acids altered, only a single tyrosine mutant (Y166F) showed any significant decrease in activity suggesting this residue is critical for proper substrate binding and/or catalysis.