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

aminohydrolase (ADAL) has been shown to be involved in the metabolism of N-methyl-AMP, a proposed intermediate during mA-modified RNA metabolism, which can be subsequently incorporated into newly synthesized RNA by Pol II. It has been proposed that ADAL will prevent N-methyl-AMP reuse and catabolize it to inosine monophosphate (IMP). Here, we have solved the crystal structures of ADAL in the apo form and in complex with GMP and IMP in the presence of Zn. We have identified the substrate-binding pocket of ADAL 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.