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PDBsum entry 2dpy
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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 similarity between the flagellar type III atpase flii and f1-Atpase subunits.
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Authors
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K.Imada,
T.Minamino,
A.Tahara,
K.Namba.
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Ref.
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Proc Natl Acad Sci U S A, 2007,
104,
485-490.
[DOI no: ]
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PubMed id
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Abstract
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Construction of the bacterial flagellum in the cell exterior proceeds at its
distal end by highly ordered self-assembly of many different component proteins,
which are selectively exported through the central channel of the growing
flagellum by the flagellar type III export apparatus. FliI is the ATPase of the
export apparatus that drives the export process. Here we report the 2.4 A
resolution crystal structure of FliI in the ADP-bound form. FliI consists of
three domains, and the whole structure shows extensive similarities to the alpha
and beta subunits of F0F1-ATPsynthase, a rotary motor that drives the chemical
reaction of ATP synthesis. A hexamer model of FliI has been constructed based on
the F1-ATPase structure composed of the alpha3beta3gamma subunits. Although the
regions that differ in conformation between FliI and the F1-alpha/beta subunits
are all located on the outer surface of the hexamer ring, the main chain
structures at the subunit interface and those surrounding the central channel of
the ring are well conserved. These results imply an evolutionary relation
between the flagellum and F0F1-ATPsynthase and a similarity in the mechanism
between FliI and F1-ATPase despite the apparently different functions of these
proteins.
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Figure 2.
Fig. 2. Structure of FliI(  1–18). (A) C^  ribbon
drawing of FliI( 1–18). All of the
secondary structure elements are labeled as in Fig. 1. The
linker connecting the N-terminal and ATPase domains, which is
missing in the model, is indicated by a dashed line. (B)
Close-up stereoview of the nucleotide-binding site. The bound
ADP is colored green, and the residues interacting with ADP are
shown in cyan. Conserved residues involved in catalysis are
indicated by yellow. (C–F) Comparison of the relative domain
orientation. FliI( 1–18) (cyan) is
superimposed onto the F[1]-  subunits in various
states, for which only corresponding atoms in the ATPase domain
were used for fitting: (C) [E] (green), (D) [TP]
(magenta), (E) [DP] (yellow) in 1BMF
(21), and (F) [ADP+Pi] (red) in 1H8E
(22).
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Figure 3.
Fig. 3. FliI hexamer model. (A) Stereoview of the ribbon
diagram. (B–D) Superposition of FliI (blue and yellow) onto
the (blue green) and (orange)
subunits of F[1]-ATPase [1BMF (ref. 21)]. (B) N-terminal domain.
(C) ATPase domain. (D) C-terminal domain. The N and C termini of
the model are labeled for one subunit in B and D, respectively.
(E–H) Electrostatic surface potential of the FliI hexamer. (E)
Side view of two opposite subunits. (F) End-on view from the
C-terminal side. (G) End-on view of a cross-section from the
C-terminal side. (H) End-on view from the N-terminal side. Black
and gray arrows indicate the hydrophobic and acidic sleeves,
respectively. The surface potential is color coded as blue
(positive) or red (negative).
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