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Structural Mechanism of Jordan's Syndrome


EMSL Project ID
51297

Abstract

Protein phosphatase 2A (PP2A) is an essential and major serine/threonine phosphatase in all eukaryotic cells, and regulates multiple cellular processes and signaling events. Deregulation of PP2A and alterations in its subunits are implicated in multiple human diseases, including multiple types of cancers, cardiac, neurological, and developmental disorders. Recently, by whole-genome sequencing, scientists have identified a series of de novo mutations in PP2A genes associated with intellectual and developmental disorders. B’?, encoded by PPP2R5D, is a member of the B’ family of regulatory subunits and plays an essential role in neurodevelopment and brain functions. Missense mutations in PPP2R5D cause severe intellectual and developmental disorders, known as Jordan’s Syndrome. More than a hundred patients have been diagnosed to have Jordan’s Syndrome, rapid growth in merely two years. To understand the fundamental mechanism of the diseases and develop a solution to reverse the defects of the gene function, we aim to obtain at least three cryo-EM structures, a wild-type and two representative disease-causing mutants, of the PP2A- B’? holoenzyme. Built on our long-term experience and expertise on the structural biology of PP2A, we have assembled and biochemically characterized up to ten mutant holoenzymes. Consistent with the range of severeness and partially overlapping symptoms caused by these mutants, our biochemical studies stratify the disease mutants into two groups that are expected to have distinct structural mechanisms. We have performed extensive preliminary characterization of the wild type and mutant complexes. Based on recent experience with PNCC, it is our strong belief that cryo-EM at PNCC will be the most helpful strategy for us to pursue the high-resolution cryo-EM structures of these complexes. We expect to use the 300keV Titan Krios instrument at the center to collect data on wild-type and two mutants (E200K and E198K) of PP2A-B’? holoenzymes. By comparing the structural difference between the wild type and mutant complexes, we will not only provide structural insights into the disease mechanisms but also expect to facilitate drug discovery and development of therapeutic approaches for patients. Built our results at the center, we will also elucidate the mode-of-action of therapeutics bound to the mutant holoenzymes in the future.

Project Details

Start Date
2020-03-15
End Date
2021-03-17
Status
Closed

Team

Principal Investigator

Yongna Xing
Institution
University of Wisconsin, Madison

Team Members

VIJAYA KUMAR BALAKRISHNAN
Institution
University of Wisconsin, Madison

Ramya Sundaresan
Institution
University of Wisconsin, Madison

Kenneth Satyshur
Institution
University of Wisconsin, Madison

Cheng-Guo Wu
Institution
University of Wisconsin, Madison

Yitong Li
Institution
University of Wisconsin, Madison

Janette Myers
Institution
Oregon Health & Science University

Irina El Khoury
Institution
Environmental Molecular Sciences Laboratory

Trevor Moser
Institution
Environmental Molecular Sciences Laboratory