PMID: 22940584 , Related PDB id: 3V4Y
Authors:
O'Connell N, Nichols SR, Heroes E, Beullens M, Bollen M, Peti W, Page R
Title:
The molecular basis for substrate specificity of the nuclear NIPP1:PP1 holoenzyme.
Journal:
Structure. 2012 Oct 10;20(10):1746-56. doi: 10.1016/j.str.2012.08.003. Epub 2012 , Aug 30.
Abstract:
Regulation of protein phosphatase 1 (PP1) is controlled by a diverse array of regulatory proteins. However, how these proteins direct PP1 specificity is not well understood. More than one-third of the nuclear pool of PP1 forms a holoenzyme with the nuclear inhibitor of PP1, NIPP1, to regulate chromatin remodeling, among other essential biological functions. Here, we show that the PP1-binding domain of NIPP1 is an intrinsically disordered protein, which binds PP1 in an unexpected manner. NIPP1 forms an alpha helix that engages PP1 at a unique interaction site, using polar rather than hydrophobic contacts. Importantly, the structure also reveals a shared PP1 interaction site outside of the RVxF motif, the PhiPhi motif. Finally, we show that NIPP1:PP1 substrate selectivity is determined by altered electrostatics and enhanced substrate localization. Together, our results provide the molecular basis by which NIPP1 directs PP1 substrate specificity in the nucleus.