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PDBsum entry 2y43
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References listed in PDB file
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Key reference
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Title
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Symmetry and asymmetry of the ring-Ring dimer of rad18.
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Authors
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A.Huang,
R.G.Hibbert,
R.N.De jong,
D.Das,
T.K.Sixma,
R.Boelens.
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Ref.
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J Mol Biol, 2011,
410,
424-435.
[DOI no: ]
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PubMed id
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Abstract
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The human ubiquitin-conjugating enzyme Rad6 (E2), with ubiquitin ligase enzyme
Rad18 (RING E3), monoubiquitinates proliferating cell nuclear antigen at stalled
replication forks in DNA translesion synthesis. Here, we determine the structure
of the homodimeric Rad18 RING domains by X-ray crystallography and classify it
to RING-RING dimers that dimerize through helices adjacent to the RING domains
and through the canonical RING domains. Using NMR spectroscopy and site-directed
mutagenesis, we demonstrate that the Rad6b binding site, for the Rad18 RING
domain, strongly resembles that of other E2/E3 RING/U-box complexes. We show
that the homodimeric Rad18 RING domain can recruit two Rad6b E2 enzymes, whereas
the full-length Rad18 homodimer binds only to a single Rad6b molecule. Such
asymmetry is a common feature of RING-RING heterodimers and has been observed
for the CHIP U-box homodimer. We propose that asymmetry may be a common feature
of dimeric RING E3 ligases.
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