E2 interaction and dimerization in the crystal structure of TRAF6.
Tumor necrosis factor (TNF) receptor-associated factor (TRAF)-6 mediates Lys63-linked polyubiquitination for NF-kappaB activation via its N-terminal RING and zinc finger domains. Here we report the crystal structures of TRAF6 and its complex with the ubiquitin-conjugating enzyme (E2) Ubc13. The RING and zinc fingers of TRAF6 assume a rigid, elongated structure. Interaction of TRAF6 with Ubc13 involves direct contacts of the RING and the preceding residues, and the first zinc finger has a structural role. Unexpectedly, this region of TRAF6 is dimeric both in the crystal and in solution, different from the trimeric C-terminal TRAF domain. Structure-based mutagenesis reveals that TRAF6 dimerization is crucial for polyubiquitin synthesis and autoubiquitination. Fluorescence resonance energy transfer analysis shows that TRAF6 dimerization induces higher-order oligomerization of full-length TRAF6. The mismatch of dimeric and trimeric symmetry may provide a mode of infinite oligomerization that facilitates ligand-dependent signal transduction of many immune receptors.
Yin
Qian
Q
Weill Medical College of Cornell University, New York, New York, USA.
Lin
Su-Chang
SC
Lamothe
Betty
B
Lu
Miao
M
Lo
Yu-Chih
YC
Hura
Gregory
G
Zheng
Lixin
L
Rich
Rebecca L
RL
Campos
Alejandro D
AD
Myszka
David G
DG
Lenardo
Michael J
MJ
Darnay
Bryant G
BG
Wu
Hao
H
D018360:Crystallography, X-Ray; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D011487:Protein Conformation; D055503:Protein Multimerization; D054829:RING Finger Domains; D048029:TNF Receptor-Associated Factor 6 / Q000737:chemistry*; D044763:Ubiquitin-Conjugating Enzymes / Q000737:chemistry*; D054875:Ubiquitination; D016335:Zinc Fingers
D048029:TNF Receptor-Associated Factor 6; C471607:UBE2N protein, human; D044763:Ubiquitin-Conjugating Enzymes