Characterization of the interactions between inhibitor-1 and recombinant PP1 by NMR spectroscopy.
 

Characterization of the interactions between inhibitor-1 and recombinant PP1 by NMR spectroscopy.

Related Articles Characterization of the interactions between inhibitor-1 and recombinant PP1 by NMR spectroscopy.

Sci Rep. 2018 Jan 08;8(1):50

Authors: Liang CT, Lin YS, Huang YC, Huang HL, Yang JQ, Wu TH, Chang CF, Huang SJ, Huang HB, Lin TH

Abstract
Inhibitor-1 is converted into a potent inhibitor of native protein phosphatase-1 (PP1) when Thr35 is phosphorylated by cAMP-dependent protein kinase (PKA). However, PKA-phosphorylated form of inhibitor-1 displayed a weak activity in inhibition of recombinant PP1. The mechanism for the impaired activity of PKA-phosphorylated inhibitor-1 toward inhibition of recombinant PP1 remained elusive. By using NMR spectroscopy in combination with site-directed mutagenesis and inhibitory assay, we found that the interaction between recombinant PP1 and the consensus PP1-binding motif of PKA-thiophosphorylated form of inhibitor-1 was unexpectedly weak. Unlike binding to native PP1, the subdomains 1 (residues around and including the phosphorylated Thr35) and 2 (the consensus PP1-binding motif) of PKA-thiophosphorylated form of inhibitor-1 do not exhibit a synergistic effect in inhibition of recombinant PP1. This finding implied that a slight structural discrepancy exists between native and recombinant PP1, resulting in PKA-thiophosphorylated form of inhibitor-1 displaying a different affinity to native and recombinant enzyme.


PMID: 29311589 [PubMed - in process]



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