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PDBsum entry 3fmp
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Oncoprotein/hydrolase
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PDB id
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3fmp
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References listed in PDB file
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Key reference
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Title
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Structural and functional analysis of the interaction between the nucleoporin nup214 and the dead-Box helicase ddx19.
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Authors
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J.Napetschnig,
S.A.Kassube,
E.W.Debler,
R.W.Wong,
G.Blobel,
A.Hoelz.
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Ref.
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Proc Natl Acad Sci U S A, 2009,
106,
3089-3094.
[DOI no: ]
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PubMed id
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Abstract
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Key steps in the export of mRNA from the nucleus to the cytoplasm are the
transport through the nuclear pore complex (NPC) and the subsequent remodeling
of messenger RNA-protein (mRNP) complexes that occurs at the cytoplasmic side of
the NPC. Crucial for these events is the recruitment of the DEAD-box helicase
Ddx19 to the cytoplasmic filaments of the NPC that is mediated by the
nucleoporin Nup214. Here, we present the crystal structure of the Nup214
N-terminal domain in complex with Ddx19 in its ADP-bound state at 2.5 A
resolution. Strikingly, the interaction surfaces are not only evolutionarily
conserved but also exhibit strongly opposing surface potentials, with the
helicase surface being positively and the Nup214 surface being negatively
charged. We speculate that the positively charged surface of the interacting
ADP-helicase binds competitively to a segment of mRNA of a linearized mRNP,
passing through the NPC on its way to the cytoplasm. As a result, the
ADP-helicase would dissociate from Nup214 and replace a single bound protein
from the mRNA. One cycle of protein replacement would be accompanied,
cooperatively, by nucleotide exchange, ATP hydrolysis, release of the
ADP-helicase from mRNA and its rebinding to Nup214. Repeat of these cycles would
remove proteins from a mRNP, one at a time, akin to a ratchet mechanism for mRNA
export.
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Figure 1.
The 6D7A loop of the Nup214 NTD is essential for Ddx19
binding. (A) Domain organization of Nup214 and Ddx19. For Ddx19,
the N-terminal extension (NTE, orange) and the 2 RecA-like
domains (domain 1 and 2, green and light orange) are indicated.
For Nup214, the β-propeller domain (light blue) and its
C-terminal extension (CTE, yellow), the coiled-coil domain
(gray), and the C-terminal unstructured region containing
numerous FG-repeats (white) are indicated. The Nup214 NTD is
composed of the β-propeller domain followed by the CTE. The
bars above the domain structures mark the fragments of the
orthorhombic crystal form. (B) Gel filtration profiles of
full-length wild-type Ddx19 incubated with the Nup214 NTD,
Nup214 NTD 1–405, or Nup214 NTD Δ6D7A before injection.
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Figure 2.
Overview of the Nup214 NTD·Ddx19 NTD structure. Ribbon
representation of the Nup214 NTD·Ddx19 NTD complex
(Upper). A 90° rotated view is shown in Lower. For the
Nup214 NTD, the β-propeller domain (blue), the 6D7A loop
(magenta), the C-terminal extension (CTE; yellow), and the blade
numbers are indicated. For the Ddx19 NTD, the N-terminal
RecA-like domain (green) and the unique N-terminal extension
(NTE; orange) is indicated. The ADP molecule bound to the Ddx19
NTD is shown in ball-and-stick representation.
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