Structural elements that modulate the substrate specificity of plant purple acid phosphatases: avenues for improved phosphorus acquisition in crops

•Purple acid phosphatases (PAPs) play an important role in phosphate acquisition.•Plants possess PAPs with diverse substrate specificities (e.g.phytate, ATP).•Structures of a PAP with bound ATP mimics provide insight into substrate binding.•Sequence analysis identifies a motif characteristic for PAPs with phytase activity.•PAPs may be engineered specifically to enhance phytase activity.