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PDBsum entry 1oe9
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Atpase/myosin
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PDB id
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1oe9
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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A structural state of the myosin V motor without bound nucleotide.
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Authors
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P.D.Coureux,
A.L.Wells,
J.Ménétrey,
C.M.Yengo,
C.A.Morris,
H.L.Sweeney,
A.Houdusse.
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Ref.
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Nature, 2003,
425,
419-423.
[DOI no: ]
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PubMed id
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Abstract
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The myosin superfamily of molecular motors use ATP hydrolysis and
actin-activated product release to produce directed movement and force. Although
this is generally thought to involve movement of a mechanical lever arm attached
to a motor core, the structural details of the rearrangement in myosin that
drive the lever arm motion on actin attachment are unknown. Motivated by kinetic
evidence that the processive unconventional myosin, myosin V, populates a unique
state in the absence of nucleotide and actin, we obtained a 2.0 A structure of a
myosin V fragment. Here we reveal a conformation of myosin without bound
nucleotide. The nucleotide-binding site has adopted new conformations of the
nucleotide-binding elements that reduce the affinity for the nucleotide. The
major cleft in the molecule has closed, and the lever arm has assumed a position
consistent with that in an actomyosin rigor complex. These changes have been
accomplished by relative movements of the subdomains of the molecule, and reveal
elements of the structural communication between the actin-binding interface and
nucleotide-binding site of myosin that underlie the mechanism of
chemo-mechanical transduction.
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Figure 2.
Figure 2: Nucleotide-binding site and distortion of the
beta- -sheet
at the interface of the N-terminal and upper 50-kDa subdomains.
a, Shown is an overlay of the  -sheet
(N-terminal subdomain superimposed) between myosin V in blue and
near rigor (Dictyostelium myosin II) in grey. Note that strands
5 -7, which belong to the upper 50-kDa subdomain are distorted
to allow the upper 50-kDa rotation that removes switch I from
the nucleotide-binding site. b, The positions of the
nucleotide-binding elements are shown for three myosin states.
The yellow asterisk in the myosin V structure marks the position
of the Mg2+ in the other structures. In the transition state,
switch II contributes to coordination of the  -phosphate
of the nucleotide, but it bends in myosin V in the opposite
direction and forms direct interactions (broken green lines)
with the fourth -strand
and the P loop of the N-terminal subdomain.
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Figure 3.
Figure 3: The actin -myosin interface. a, Myosin V as viewed
from the actin side of the interface reveals the positioning of
putative actin-binding elements. b, The same view of myosin V is
overlaid on the lower 50-kDa subdomains of Dictyostelium myosin
II structures. Note the conformational change in the strut and
the obvious rotation of the upper 50-kDa subdomain towards the
actin filament (represented by an arrow) in the myosin V
structure. c, The myosin V and transition state actin-binding
elements are docked on an actin filament, maintaining the
identical positioning of the lower 50-kDa subdomain in both
cases. In myosin V, the HCM loop has been repositioned in such a
way that it can directly contribute to actin binding.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nature
(2003,
425,
419-423)
copyright 2003.
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