PDBsum entry 1k2f

Ligase, protein binding

PDB id: 1k2f

Contents

Protein chains

190 a.a. *

Ligands

BME ×4

Metals

_ZN ×6

Waters ×65

* Residue conservation analysis

PDB id:

1k2f

Name:

Ligase, protein binding

Title:

Siah, seven in absentia homolog

Structure:

Siah-1a protein. Chain: a, b. Fragment: c-terminal domain (residues 93-282). Synonym: seven in absentia 1a. Engineered: yes

Source:

Mus musculus. House mouse. Organism_taxid: 10090. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PQS)

Resolution:

2.60Å R-factor: 0.220 R-free: 0.277

Authors:

G.Polekhina,C.M.House,N.Traficante,J.P.Mackay,F.Relaix,D.A.Sassoon, M.W.Parker,D.D.L.Bowtell

Key ref:

G.Polekhina et al. (2002). Siah ubiquitin ligase is structurally related to TRAF and modulates TNF-alpha signaling. Nat Struct Biol, 9, 68-75. PubMed id: 11742346 DOI: 10.1038/nsb743

Date:

26-Sep-01 Release date: 28-Dec-01

Protein chains

P61092  (SIA1A_MOUSE) -  E3 ubiquitin-protein ligase SIAH1A from Mus musculus

Seq: 282 a.a.

Struc: 190 a.a.

Enzyme reactions

• Enzyme class: E.C.2.3.2.27 - RING-type E3 ubiquitin transferase.
• Reaction: S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N₆- ubiquitinyl-[acceptor protein]-L-lysine

DOI no: 10.1038/nsb743

Nat Struct Biol 9:68-75 (2002)

PubMed id: 11742346

Siah ubiquitin ligase is structurally related to TRAF and modulates TNF-alpha signaling.

G.Polekhina, C.M.House, N.Traficante, J.P.Mackay, F.Relaix, D.A.Sassoon, M.W.Parker, D.D.Bowtell.

ABSTRACT

Members of the Siah (seven in absentia homolog) family of RING domain proteins are components of E3 ubiquitin ligase complexes that catalyze ubiquitination of proteins. We have determined the crystal structure of the substrate-binding domain (SBD) of murine Siah1a to 2.6 A resolution. The structure reveals that Siah is a dimeric protein and that the SBD adopts an eight-stranded beta-sandwich fold that is highly similar to the TRAF-C region of TRAF (TNF-receptor associated factor) proteins. The TRAF-C region interacts with TNF-alpha receptors and TNF-receptor associated death-domain (TRADD) proteins; however, our findings indicate that these interactions are unlikely to be mimicked by Siah. The Siah structure also reveals two novel zinc fingers in a region with sequence similarity to TRAF. We find that the Siah1a SBD potentiates TNF-alpha-mediated NF-kappa B activation. Therefore, Siah proteins share important similarities with the TRAF family of proteins, including their overall domain architecture, three-dimensional structure and functional activity.

Selected figure(s)

Figure 4.
Figure 4. Similarities between Siah and TRAF. a, Comparison of the domain architecture of Siah and TRAF2 proteins. Pink circle represents the RING domain; blue bar, zinc finger; red rod, coiled-coil; and green rod, TRAF-C domain. b, Siah1a SBD stimulation of an NF- B reporter assay in 293 cells. Cells were transfected with Siah1a, Siah1a SBD, TRAF2 or TNF- and combinations of TNF- -Siah1a and TNF- -Siah1a SBD. Cotransfection of the I B super repressor was able to reduce NF- B activation to background levels for all points measured (data not shown).

Figure 5.
Figure 5. Surface features of Siah SBD. a, Surface of Siah1a SBD dimer with the zinc fingers shown in blue and the C-terminal domains in green. Areas of strictly conserved residues are shown in red. b,c, Views of SBD after successive 90° rotations along the long axis of the molecule. A putative RING interacting region (see text) is indicated by the arrows in (a,c). A star in (b) highlights a potential binding partner/substrate site (see text). Images were generated by GRASP60.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2002, 9, 68-75) copyright 2002.

Figures were selected by an automated process.