May be a ligase forming an amide bond. Shows ATPase activity. Despite its similarity to the C-terminal synthetase domain of Gss, is not a glutathionylspermidine (Gsp) synthetase. Cannot synthesize Gsp, glutathione (GSH), or GSH intermediates, from GSH and spermidine, cysteine and glutamate, gamma-glutamylcysteine and spermidine, and gamma-glutamylcysteine and glycine. Does not bind to Gsp. Deletion of this gene does not affect the ability to synthesize glutathionylspermidine. There is no visible differences between wild-type and mutant strain growth in LB media. Belongs to the glutathionylspermidine synthase preATP-grasp family.