Research ArticleStructural Biology

Structural basis for the preference of the Arabidopsis thaliana phosphatase RLPH2 for tyrosine-phosphorylated substrates

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Science Signaling  03 Apr 2018:
Vol. 11, Issue 524, eaan8804
DOI: 10.1126/scisignal.aan8804

Substrate specificity of an unusual phosphatase

The plant phosphatase RLPH2 is a member of the phosphoserine- and phosphothreonine-specific protein phosphatase (PPP) family; however, it prefers substrates that contain phosphotyrosine residues to those that contain phosphoserine or phosphothreonine residues. Labandera et al. solved crystal structures of RLPH2 both in its native form and in complex with the phosphate mimic tungstate and performed biochemical assays with various mutant forms of RLPH2. These approaches revealed the structural basis for the preference of RLPH2 for phosphotyrosine, particularly substrates that are dually phosphorylated on both tyrosine and a nearby threonine residue. These findings explain the unusual properties of this phosphatase, and the preference for substrates containing a pTxpY motif suggests that mitogen-activated protein kinases (MAPKs) may be substrates for RLPH2 in vivo.