# Structural dynamics and function of the COP9 signalosome

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2020 · $309,000

## Abstract

The COP9 signalosome (CSN) is an evolutionally conserved, essential multi-subunit protein complex critical for
controlling diverse cellular and developmental processes in animals and plants. With 8 subunits (CSN1-CSN8),
CSN functions as a deneddylase responsible for cleaving ubiquitin-like protein Nedd8 modification from
neddylated substrates including cullin proteins, the key components of Cullin–RING ubiquitin E3 ligases
(CRLs). CRLs represent the largest superfamily of multi-subunit E3s with more than 240 members, which
orchestrate ~20% of protein degradation in the ubiquitin-proteasome system (UPS). The biological significance
of CSN in eukaryotic biology is manifested by its function in controlling CRL activity and CRL-mediated protein
degradation. CSN dysregulation has been implicated in many human diseases including cancers, and CSN
inhibition has shown great potential for cancer therapy. A comprehensive understanding of how CSN works in
cells is essential to uncovering molecular details underlying CSN biology and defining its role in human health
and medicine. Recent structural analysis has revealed CSN architecture at medium resolution, and discovered
that free CSN exists in an inactive state. It has been shown that CSN auto-inhibition can only be released
through binding to neddylated cullins to induce substantial conformational changes required for CSN activation.
Due to structural differences in numerous interchangeable substrate receptors (SRs), human CRLs have
extremely high structural diversities within the family. Despite extensive structural studies, it remains unknown
how CSN interacts with diverse structures of CRLs in cells to release its auto-inhibition and enable its function
in regulating CRLs. We hypothesize that CSN might use dynamic topology to recognize and accommodate
different CRLs. Due to limitations in traditional structural tools, novel approaches that can probe highly dynamic
structures, compare a wide spectrum of conformational changes, as well as characterize in vivo structural
topologies of large heterogeneous protein complexes, are needed to test this hypothesis. Recent work
suggests that cross-linking mass spectrometry (XL-MS) is best suited for validating our hypothesis as it
possesses all of the required capabilities. Therefore, we propose to develop and employ novel XL-MS
technologies to effectively dissect the full-range of structural dynamics and conformational changes associated
with CSN activation and function in vitro and in cells. To this end, our specific aims are 1) probing the structural
dynamics of CSN using a combinatory XL-MS approach; 2) mapping conformational changes of CSN upon
binding to CRLs in vitro and in vivo. The proposed project will not only help address important yet unresolved
biological questions associated with CSN activation and function, but also propel quantitative XL-MS studies to
a new level for studying dynamics and heterogeneous protein complexes in vitro and in vivo.

## Key facts

- **NIH application ID:** 9999636
- **Project number:** 5R01GM130144-03
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** Lan Huang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $309,000
- **Award type:** 5
- **Project period:** 2018-09-15 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9999636

## Citation

> US National Institutes of Health, RePORTER application 9999636, Structural dynamics and function of the COP9 signalosome (5R01GM130144-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9999636. Licensed CC0.

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