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PDBsum entry 2fwr
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DNA binding protein
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PDB id
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2fwr
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References listed in PDB file
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Key reference
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Title
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Conserved xpb core structure and motifs for DNA unwinding: implications for pathway selection of transcription or excision repair.
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Authors
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L.Fan,
A.S.Arvai,
P.K.Cooper,
S.Iwai,
F.Hanaoka,
J.A.Tainer.
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Ref.
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Mol Cell, 2006,
22,
27-37.
[DOI no: ]
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PubMed id
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Abstract
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The human xeroderma pigmentosum group B (XPB) helicase is essential for
transcription, nucleotide excision repair, and TFIIH functional assembly. Here,
we determined crystal structures of an Archaeoglobus fulgidus XPB homolog
(AfXPB) that characterize two RecA-like XPB helicase domains and discover a DNA
damage recognition domain (DRD), a unique RED motif, a flexible thumb motif
(ThM), and implied conformational changes within a conserved functional core.
RED motif mutations dramatically reduce helicase activity, and the DRD and ThM,
which flank the RED motif, appear structurally as well as functionally analogous
to the MutS mismatch recognition and DNA polymerase thumb domains. Substrate
specificity is altered by DNA damage, such that AfXPB unwinds dsDNA with 3'
extensions, but not blunt-ended dsDNA, unless it contains a lesion, as shown for
CPD or (6-4) photoproducts. Together, these results provide an unexpected
mechanism of DNA unwinding with implications for XPB damage verification in
nucleotide excision repair.
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Figure 5.
Figure 5. Structural Comparison of XPB HD2 Insertion ThM
with the Thumb Domain of T7 DNA Polymerase and Taq DNA Polymerase
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Figure 6.
Figure 6. Proposed Structure-Based Mechanism whereby Damage
Verification by XPB Promotes Unwinding of Damaged dsDNA for NER
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2006,
22,
27-37)
copyright 2006.
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