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PAM forms an atypical SCF ubiquitin ligase complex that ubiquitinates and degrades NMNAT2
Author(s) -
Desbois Muriel,
Crawley Oliver,
Evans Paul R.,
Baker Scott T.,
Masuho Ikuo,
Yasuda Ryohei,
Grill Brock
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.465.1
Subject(s) - ubiquitin ligase , skp1 , ubiquitin , cullin , f box protein , microbiology and biotechnology , proteasome , biology , chemistry , computational biology , genetics , gene
PHR (PAM/Highwire/RPM‐1) proteins are conserved RING E3 ubiquitin ligases that function in developmental processes, such as axon termination and synapse formation, as well as axon degeneration. At present, our understanding of how PHR proteins form ubiquitin ligase complexes remains incomplete. Although genetic studies indicate NMNAT2 is an important mediator of PHR protein function in axon degeneration, it remains unknown how PHR proteins inhibit NMNAT2. Here, we decipher the biochemical basis for how the human PHR protein PAM, also called MYCBP2, forms a noncanonical Skp/Cullin/F box (SCF) complex that contains the F‐box protein FBXO45 and SKP1 but lacks CUL1. We show FBXO45 does not simply function in substrate recognition but is important for assembly of the PAM/FBXO45/SKP1 complex. Interestingly, we demonstrate a novel role for SKP1 as an auxiliary component of the target recognition module that enhances binding of FBXO45 to NMNAT2. Finally, we provide biochemical evidence that PAM polyubiquitinates NMNAT2 and regulates NMNAT2 protein stability and degradation by the proteasome. Support or Funding Information National Institutes of Health Grant R01 NS072129 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .