Structure of Arabidopsis thaliana N 6 -methyl-AMP deaminase ADAL with bound GMP and IMP and implications for N 6 -methyl-AMP recognition and processing.

Arabidopsis thaliana aminohydrolase (AtADAL) has been shown to be involved in the metabolism of N-6-methyl-AMP, a proposed intermediate during m(6)A-modified RNA metabolism, which can be subsequently incorporated into newly synthesized RNA by Pol II. It has been proposed that AtADAL will prevent N-6-methyl-AMP reuse and catabolize it to inosine monophosphate (IMP). Here, we have solved the crystal structures of AtADAL in the apo form and in complex with GMP and IMP in the presence of Zn2+. We have identified the substrate-binding pocket of AtADAL and compared it with that for adenosine deaminase (ADA), adenine deaminase (ADE) and AMP deaminase (AMPD) from multiple species. The comparisons reveal that plant ADAL1 may have the potential ability to catalyze different alkyl-group substituted substrates.