PHLPP2 is a pseudophosphatase that lost activity in the metazoan ancestor
Abstract
The phosphoinositide 3-kinase (PI3K) pathway is a major regulator of cell and organismal growth. Consequently, hyperactivation of PI3K and its downstream effector kinase, Akt, is observed in many human cancers. Pleckstrin homology domain leucine-rich repeat-containing protein phosphatases (PHLPP), two paralogous members of the metal-dependent protein phosphatase family, have been reported as negative regulators of Akt signaling and, therefore, tumor suppressors. However, the stoichiometry and identity of the bound metal ion(s), mechanism of action, and enzymatic specificity of these proteins are not known. Seeking to fill these gaps in our understanding of PHLPP biology, we unexpectedly found that PHLPP2 has no catalytic activity in vitro. Instead, we found that PHLPP2 is a pseudophosphatase with a single zinc ion bound in its catalytic center. Furthermore, we found that cancer genomics data do not support the proposed role of PHLPP1 or PHLPP2 as tumor suppressors. Phylogenetic analyses revealed an ancestral phosphatase that arose more than 1,000 Mya, but that lost activity at the base of the metazoan lineage. Surface conservation indicates that while PHLPP2 has lost catalytic activity, it may have retained substrate binding. Finally, using phylogenomics, we identify coevolving genes consistent with a scaffolding role for PHLPP2 on membranes. In summary, our results provide a molecular explanation for the inconclusive results that have hampered research on PHLPP and argue for a focus on the noncatalytic roles of PHLPP1 and PHLPP2.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (25)
Tarik Husremović
Max Perutz Labs, University of Vienna and Medical University of Vienna
Vanessa Meier
Max Perutz Labs, University of Vienna and Medical University of Vienna
Lucas Piëch
Max Perutz Labs, University of Vienna and Medical University of Vienna
Katharina M. Siess
Max Perutz Labs, University of Vienna and Medical University of Vienna
Sumire Antonioli
Max Perutz Labs, University of Vienna and Medical University of Vienna
Irina Grishkovskaya
Research Institute of Molecular Pathology, Vienna BioCenter
Nikoleta Kircheva
Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences
Silvia E. Angelova
Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences
Karoline Wenzl
Max Perutz Labs, University of Vienna and Medical University of Vienna
Andreas Brandstätter
Department of Chemistry, Institute of Analytical Chemistry, University of Natural Resources and Life Sciences
Jiri Veis
Max Perutz Labs, University of Vienna and Medical University of Vienna
Fran Miočić-Stošić
Max Perutz Labs, University of Vienna and Medical University of Vienna
Dorothea Anrather
Max Perutz Labs, Mass Spectrometry Facility, Vienna Biocenter Campus
Markus Hartl
Max Perutz Labs, Mass Spectrometry Facility, Vienna Biocenter Campus
Linda Truebestein
Max Perutz Labs, University of Vienna and Medical University of Vienna
Luis M. Cerron-Alvan
Max Perutz Labs, University of Vienna and Medical University of Vienna
Martin Leeb
Max Perutz Labs, University of Vienna and Medical University of Vienna
Bojan Žagrović
Max Perutz Labs, University of Vienna and Medical University of Vienna
Stephan Hann
Department of Chemistry, Institute of Analytical Chemistry, University of Natural Resources and Life Sciences
Christoph Bock
Egon Ogris
Max Perutz Labs, University of Vienna and Medical University of Vienna
Todor Dudev
Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”
Nicholas A. T. Irwin
Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter
David Haselbach
Research Institute of Molecular Pathology, Vienna BioCenter
Thomas A. Leonard
Max Perutz Labs, University of Vienna and Medical University of Vienna