Journal article
Molecular Determinants for PP2A Substrate Specificity: Charged Residues Mediate Dephosphorylation of Tyrosine Hydroxylase by the PP2A/B′ Regulatory Subunit
Biochemistry (Easton), Vol.49(5), pp.986-995
02/09/2010
DOI: 10.1021/bi902160t
PMCID: PMC3012350
PMID: 20017541
Abstract
Together with protein phosphatase 1, protein phosphatase 2A (PP2A) contributes the bulk of Ser/Thr phosphatase activity in most cell types. The predominant form of PP2A is a heterotrimer of catalytic (C), scaffolding (A), and diverse regulatory subunits (B, B′, and B′′). We have previously shown that N-terminal phosphorylation sites in tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, are specifically dephosphorylated by PP2A holoenzymes containing the B′β regulatory subunit. Here, we identify a Glu residue conserved in B′ regulatory subunits that is critical for dephosphorylation and inactivation of tyrosine hydroxylase in vitro and in PC12 cells. According to the PP2A heterotrimer crystal structure, Glu153 (B′β numbering) abuts the catalytic site on the C subunit, and we demonstrate that Glu153 substitution inhibits multisite TH dephosphorylation without compromising PP2A/B′β holoenzyme assembly or in vitro dephosphorylation of model substrates. Apart from its role in modulating TH activity, Glu153 is also necessary for PP2A/B′β-mediated enhancement of nerve growth factor signaling. Furthermore, global phosphoproteome analysis suggests that Glu153 mediates dephosphorylation of most B′β substrates in PC12 cells. With regard to selectivity determinants in the substrate, we show that B′β Glu153 recognizes Arg37 and Arg38 in TH to direct dephosphorylation of both upstream (Ser31) and downstream (Ser40) sites. These results provide evidence of a subunit-spanning substrate docking site on the PP2A/B′ holoenzyme, in which negatively charged side chains in the regulatory subunit interact with positive charges proximal to phosphorylated residues to mediate site-specific dephosphorylation.
Details
- Title: Subtitle
- Molecular Determinants for PP2A Substrate Specificity: Charged Residues Mediate Dephosphorylation of Tyrosine Hydroxylase by the PP2A/B′ Regulatory Subunit
- Creators
- Amit SarafElizabeth A ObergStefan Strack
- Resource Type
- Journal article
- Publication Details
- Biochemistry (Easton), Vol.49(5), pp.986-995
- DOI
- 10.1021/bi902160t
- PMID
- 20017541
- PMCID
- PMC3012350
- NLM abbreviation
- Biochemistry
- ISSN
- 0006-2960
- eISSN
- 1520-4995
- Publisher
- American Chemical Society
- Language
- English
- Date published
- 02/09/2010
- Academic Unit
- Pathology; Iowa Neuroscience Institute; Neuroscience and Pharmacology
- Record Identifier
- 9984040371702771
Metrics
10 Record Views