This gene from phage Hiyaa, currently gene 75 (originally draft gene 78 ) starting at base 55288 (pham 21467) shows more than 25 HHpred hits with 100% probability and 96 to 98% coverage to adenylosuccinate lyase. Here is a link to the PDB entry for 2PFM the second best HHPRED hit to this gene.

A very similar protein also in pham 21467 is gene 36 from Gordonia phage Ghobes, this gene also has the annotation of "adenylosuccinate lyase".
According to KEGG, one of the primary roles for adenylosuccinate lyase (4.3.2.2) is purine biosynthesis in which it is the second of two enzymes used to convert IMP to AMP. The first step in this pathway is "adenylosuccinate synthetase, PurA-like" which is already an approved sea-phages term.

These results would suggest (keeping the nomenclature parallel) adding
"adenylosuccinate lyase, PurB-like"
Edited 05 Oct, 2018 14:40