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PLoS One. 2014 Jul 9;9(7):e101846. doi: 10.1371/journal.pone.0101846. eCollection 2014.

Structural and biochemical characterization of human PR70 in isolation and in complex with the scaffolding subunit of protein phosphatase 2A.

Author information

1
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
2
Life Science Division, Lawrence Berkeley National Lab (LBNL), Berkeley, California, United States of America.
3
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
4
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.

Abstract

Protein Phosphatase 2A (PP2A) is a major Ser/Thr phosphatase involved in the regulation of various cellular processes. PP2A assembles into diverse trimeric holoenzymes, which consist of a scaffolding (A) subunit, a catalytic (C) subunit and various regulatory (B) subunits. Here we report a 2.0 Å crystal structure of the free B''/PR70 subunit and a SAXS model of an A/PR70 complex. The crystal structure of B''/PR70 reveals a two domain elongated structure with two Ca2+ binding EF-hands. Furthermore, we have characterized the interaction of both binding partner and their calcium dependency using biophysical techniques. Ca2+ biophysical studies with Circular Dichroism showed that the two EF-hands display different affinities to Ca2+. In the absence of the catalytic C-subunit, the scaffolding A-subunit remains highly mobile and flexible even in the presence of the B''/PR70 subunit as judged by SAXS. Isothermal Titration Calorimetry studies and SAXS data support that PR70 and the A-subunit have high affinity to each other. This study provides additional knowledge about the structural basis for the function of B'' containing holoenzymes.

PMID:
25007185
PMCID:
PMC4090178
DOI:
10.1371/journal.pone.0101846
[Indexed for MEDLINE]
Free PMC Article

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