CSNAP Is a Stoichiometric Subunit of the COP9 Signalosome

Shelly Rozen, Maria G Fuzesi-Levi, Gili Ben-Nissan, Limor Mizrachi, Alexandra Gabashvili, Yishai Levin, Shifra Ben-Dor, Miriam Eisenstein, Michal Sharon

Research output: Contribution to journalArticlepeer-review

Abstract

The highly conserved COP9 signalosome (CSN) complex is a key regulator of all cullin-RING-ubiquitin ligases (CRLs), the largest family of E3 ubiquitin ligases. Until now, it was accepted that the CSN is composed of eight canonical components. Here, we report the discovery of an additional integral and stoichiometric subunit that had thus far evaded detection, and we named it CSNAP (CSN acidic protein). We show that CSNAP binds CSN3, CSN5, and CSN6, and its incorporation into the CSN complex is mediated through the C-terminal region involving conserved aromatic residues. Moreover, depletion of this small protein leads to reduced proliferation and a flattened and enlarged morphology. Finally, on the basis of sequence and structural properties shared by both CSNAP and DSS1, a component of the related 19S lid proteasome complex, we propose that CSNAP, the ninth CSN subunit, is the missing paralogous subunit of DSS1. The highly conserved COP9 signalosome (CSN) complex is a key regulator of all cullin-RING-ubiquitin-ligases (CRLs), the largest family of E3 ubiquitin ligases. Rozen et al. report the discovery of an additional integral and stoichiometric subunit for this highly conserved complex.

Original languageEnglish
Article number2073
Pages (from-to)585-598
Number of pages14
JournalCell Reports
Volume13
Issue number3
Early online date8 Oct 2015
DOIs
StatePublished - 20 Oct 2015

All Science Journal Classification (ASJC) codes

  • General Biochemistry,Genetics and Molecular Biology

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