3CHM

Crystal structure of PCI domain from A. thaliana COP9 signalosome subunit 7 (CSN7)

Summary for 3CHM

• Entry DOI: 10.2210/pdb3chm/pdb
• Descriptor: COP9 signalosome complex subunit 7, MAGNESIUM ION, ACETATE ION, ... (4 entities in total)
• Functional Keywords: heat/arm repeats, winged helix motif, developmental protein, nucleus, phosphoprotein, phytochrome signaling pathway, signalosome, plant protein
• Biological source: Arabidopsis thaliana (Mouse-ear cress)
• Cellular location: Cytoplasm: Q94JU3
• Total number of polymer chains: 1
• Total formula weight: 19030.34

Authors

Dessau, M.,Hirsch, J.A. (deposition date: 2008-03-10, release date: 2008-10-28, Last modification date: 2024-03-13)

Primary citation

Dessau, M.,Halimi, Y.,Erez, T.,Chomsky-Hecht, O.,Chamovitz, D.A.,Hirsch, J.A.
The Arabidopsis COP9 signalosome subunit 7 is a model PCI domain protein with subdomains involved in COP9 signalosome assembly
Plant Cell, 20:2815-2834, 2008

PubMed Abstract: The COP9 Signalosome (CSN) is a multiprotein complex that was originally identified in Arabidopsis thaliana as a negative regulator of photomorphogenesis and subsequently shown to be a general eukaryotic regulator of developmental signaling. The CSN plays various roles, but it has been most often implicated in regulating protein degradation pathways. Six of eight CSN subunits bear a sequence motif called PCI. Here, we report studies of subunit 7 (CSN7) from Arabidopsis, which contains such a motif. Our in vitro and structural results, based on 1.5 A crystallographic data, enable a definition of a PCI domain, built from helical bundle and winged helix subdomains. Using functional binding assays, we demonstrate that the PCI domain (residues 1 to 169) interacts with two other PCI proteins, CSN8 and CSN1. CSN7 interactions with CSN8 use both PCI subdomains. Furthermore, we show that a C-terminal tail outside of this PCI domain is responsible for association with the non-PCI subunit, CSN6. In vivo studies of transgenic plants revealed that the overexpressed CSN7 PCI domain does not assemble into the CSN, nor can it complement a null mutation of CSN7. However, a CSN7 clone that contains the PCI domain plus part of the CSN6 binding domain can complement the null mutation in terms of seedling viability and photomorphogenesis. These transgenic plants, though, are defective in adult growth, suggesting that the CSN7 C-terminal tail plays additional functional roles. Together, the findings have implications for CSN assembly and function, highlighting necessary interactions between subunits.

PubMed: 18854373
DOI: 10.1105/tpc.107.053801

Experimental method

X-RAY DIFFRACTION (1.5 Å)