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PDBsum entry 2obl
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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 analysis of a prototypical atpase from the type III secretion system.
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Authors
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R.Zarivach,
M.Vuckovic,
W.Deng,
B.B.Finlay,
N.C.Strynadka.
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Ref.
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Nat Struct Mol Biol, 2007,
14,
131-137.
[DOI no: ]
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PubMed id
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Abstract
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The type III secretion system (T3SS) ATPase is the conserved and essential
inner-membrane component involved in the initial stages of selective secretion
of specialized T3SS virulence effector proteins from the bacterial cytoplasm
through to the infected host cell, a process crucial to subsequent
pathogenicity. Here we present the 1.8-A-resolution crystal structure of the
catalytic domain of the prototypical T3SS ATPase EscN from enteropathogenic
Escherichia coli (EPEC). Along with in vitro and in vivo mutational analysis,
our data show that the T3SS ATPases share similarity with the F1 ATPases but
have important structural and sequence differences that dictate their unique
secretory role. We also show that T3SS ATPase activity is dependent on EscN
oligomerization and describe the molecular features and possible functional
implications of a hexameric ring model.
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Figure 5.
Figure 5. Functional mutants of EscN. (a) Previously isolated
functional mutants of the Salmonella ATPase InvC (blue) mapped
on the structure of EscN with bound ATP (gold), delineating the
position of the active site. See Supplementary Figure 2 for the
corresponding numbering in Salmonella. (b) Functional mutants
created and characterized in this study. Shown are V393P
(yellow) and the mutation of the active site residue that
cooperatively binds the ATP of the adjacent monomer, Arg366
(blue).
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Figure 6.
Figure 6. The hexameric T3SS and F1 ATPases. Right, the  [3]
 [3]
heterohexamer of the F1 ATPase, with known membrane orientation
delineated by the binding of its membrane-anchored  -subunit
(purple) within the inner pore of the ATPase hexameric ring. In
yellow is the helical domain at the C terminus of the F1
ATPases, which is absent in EscN. Left, the EscN homohexamer
(blue), with the predicted docking site for the helical T3SS
chaperone (PDB 1XKP^41; red), in complex with its cognate and
partially unfolded effector (green). The functional point
mutation V393P lies at the edge of the chaperone-binding surface
(yellow).
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Mol Biol
(2007,
14,
131-137)
copyright 2007.
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