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PDBsum entry 4jqu
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Ligase/protein binding
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PDB id
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4jqu
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References listed in PDB file
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Key reference
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Title
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A structurally unique e2-Binding domain activates ubiquitination by the erad e2, Ubc7p, Through multiple mechanisms.
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Authors
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M.B.Metzger,
Y.H.Liang,
R.Das,
J.Mariano,
S.Li,
J.Li,
Z.Kostova,
R.A.Byrd,
X.Ji,
A.M.Weissman.
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Ref.
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Mol Cell, 2013,
50,
516-527.
[DOI no: ]
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PubMed id
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Abstract
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Cue1p is an integral component of yeast endoplasmic reticulum (ER)-associated
degradation (ERAD) ubiquitin ligase (E3) complexes. It tethers the ERAD
ubiquitin-conjugating enzyme (E2), Ubc7p, to the ER and prevents its
degradation, and also activates Ubc7p via unknown mechanisms. We have now
determined the crystal structure of the Ubc7p-binding region (U7BR) of Cue1p
with Ubc7p. The U7BR is a unique E2-binding domain that includes three
α-helices that interact extensively with the "backside" of Ubc7p.
Residues essential for E2 binding are also required for activation of Ubc7p and
for ERAD. We establish that the U7BR stimulates both RING-independent and
RING-dependent ubiquitin transfer from Ubc7p. Moreover, the U7BR enhances
ubiquitin-activating enzyme (E1)-mediated charging of Ubc7p with ubiquitin. This
demonstrates that an essential component of E3 complexes can simultaneously bind
to E2 and enhance its loading with ubiquitin. These findings provide mechanistic
insights into how ubiquitination can be stimulated.
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