Peroxisomal protein phosphatase PP2A-B' theta interacts with and piggybacks SINA-like 10 E3 ligase into peroxisomes

Protein phosphatase 2A (PP2A) is targeted to the plant peroxisome via a C-terminal SSL sequence on its regulatory B' theta (theta) subunit. To date the substrates of peroxisomal PP2A are unknown but are thought to be recruited by the regulatory B'theta subunit. Employing yeast two hybrid screening, we have identified Arabidopsis E3 ligase SINA-like 10 as a B'theta binding partner. The E3 ligase SINA-like 10 was found to harbor the PP2A B'-binding Short Linear interaction Motif or SLiM, LxxIxE. This interaction was further verified both in vitro and in vivo using direct pulldown assays and bimolecular fluorescence comple-mentation. Utilizing peroxisomal targeted and a cytosolic version of B'theta (lacking its C-terminal peroxi-somal targeting sequence SSL>) bimolecular fluorescence complementation suggests an interaction to occur in the cytosol followed by piggybacking E3 ligase SINA-like 10 into peroxisomes. These results identify a first peroxisomal PP2A interactor, which also obtains a PP2A B'-binding SLiM.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

Protein phosphatase 2A (PP2A) is targeted to the plant peroxisome via a C-terminal SSL sequence on its regulatory B' theta (theta) subunit. The substrates of peroxisomal PP2A are unknown but are recruited by the regulatory B'theta subunit. Arabidopsis E3 ligase SINA-like 10 was identified as a B'theta binding partner, and it interacts with PP2A through the B'-binding SLiM motif. This interaction occurs in the cytosol and SINA-like 10 is then transported into peroxisomes.