The E3 ubiquitin ligase- and protein phosphatase 2A (PP2A)-binding domains of the Alpha4 protein are both required for Alpha4 to inhibit PP2A degradation
| Autor: | Katherine L. Germane, Brian E. Wadzinski, Benjamin W. Spiller, Ping Zou, Guy R. Watkins, Michele LeNoue-Newton, Lisa R. McCorvey |
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| Rok vydání: | 2011 |
| Předmět: |
Protein subunit
Ubiquitin-Protein Ligases Amino Acid Motifs Biology Protein degradation Crystallography X-Ray Biochemistry DDB1 Mice Protein structure Ubiquitin Animals Humans Protein Phosphatase 2 Molecular Biology Adaptor Proteins Signal Transducing Binding Sites Intracellular Signaling Peptides and Proteins Ubiquitination Cell Biology Protein phosphatase 2 Phosphoproteins Ubiquitin ligase Protein Structure Tertiary Tetratricopeptide HEK293 Cells biology.protein Intercellular Signaling Peptides and Proteins Molecular Chaperones Signal Transduction |
| Zdroj: | The Journal of biological chemistry. 286(20) |
| ISSN: | 1083-351X |
| Popis: | Protein phosphatase 2A (PP2A) is regulated through a variety of mechanisms, including post-translational modifications and association with regulatory proteins. Alpha4 is one such regulatory protein that binds the PP2A catalytic subunit (PP2Ac) and protects it from polyubiquitination and degradation. Alpha4 is a multidomain protein with a C-terminal domain that binds Mid1, a putative E3 ubiquitin ligase, and an N-terminal domain containing the PP2Ac-binding site. In this work, we present the structure of the N-terminal domain of mammalian Alpha4 determined by x-ray crystallography and use double electron-electron resonance spectroscopy to show that it is a flexible tetratricopeptide repeat-like protein. Structurally, Alpha4 differs from its yeast homolog, Tap42, in two important ways: 1) the position of the helix containing the PP2Ac-binding residues is in a more open conformation, showing flexibility in this region; and 2) Alpha4 contains a ubiquitin-interacting motif. The effects of wild-type and mutant Alpha4 on PP2Ac ubiquitination and stability were examined in mammalian cells by performing tandem ubiquitin-binding entity precipitations and cycloheximide chase experiments. Our results reveal that both the C-terminal Mid1-binding domain and the PP2Ac-binding determinants are required for Alpha4-mediated protection of PP2Ac from polyubiquitination and degradation. |
| Databáze: | OpenAIRE |
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