Structural and Biochemical Characterization of Human PR70 in Isolation and in Complex with the Scaffolding Subunit of Protein Phosphatase 2A

作者：Dovega Rebecca; Tsutakawa Susan; Quistgaard E**en M; Anandapadamanaban Madhanagopal; Low Christian; Nordlund Par^*

来源：PLos One, 2014, 9(7): e101846.

DOI：10.1371/journal.pone.0101846

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 angstrom 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.

• 出版日期2014-7-9
• 单位南阳理工学院