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PDBsum entry 1lkx
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Contractile protein
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PDB id
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1lkx
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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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Crystal structure of the motor domain of a class-I myosin.
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Authors
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M.Kollmar,
U.Dürrwang,
W.Kliche,
D.J.Manstein,
F.J.Kull.
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Ref.
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EMBO J, 2002,
21,
2517-2525.
[DOI no: ]
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PubMed id
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Abstract
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The crystal structure of the motor domain of Dictyostelium discoideum myosin-IE,
a monomeric unconventional myosin, was determined. The crystallographic
asymmetric unit contains four independently resolved molecules, highlighting
regions that undergo large conformational changes. Differences are particularly
pronounced in the actin binding region and the converter domain. The changes in
position of the converter domain reflect movements both parallel to and
perpendicular to the actin axis. The orientation of the converter domain is
approximately 30 degrees further up than in other myosin structures, indicating
that MyoE can produce a larger power stroke by rotating its lever arm through a
larger angle. The role of extended loops near the actin-binding site is
discussed in the context of cellular localization. The core regions of the motor
domain are similar, and the structure reveals how that core is stabilized in the
absence of an N-terminal SH3-like domain.
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Figure 3.
Figure 3 Contacts between the relay region, converter domain and
lever arm helix allow these structural elements to move
together. (A) The relay region and SH1 helix of MyoE are shown
in cyan. In MyoE and other class-I myosins, there is a hydrogen
bond between Thr418 in the relay helix and Asn618 from the SH1
helix. (B) Close-up view of this region, viewed along the relay
helix. The kink forms at Thr418. (C) Highly conserved residues
form a hydrophobic core, and polar residues further stabilize
the link via conserved hydrogen bonds (dashed lines). This core
interaction is further supported by a small, hydrophobic, highly
conserved extension into the converter formed by residues Tyr630
and Val677 (DdTyr699 and DdIle744). At the tip of the relay loop
(cyan), conserved Glu429 (DdGlu497) forms hydrogen bonds to
residue Thr675 of the converter domain (brown) (DdThr742; at
this position there is always a threonine or a serine) and to
the backbone nitrogen atoms of converter residues Lys674 and
Lys676. (D) Hydrophobic interactions between the lever arm helix
(cyan) and core domain (white). All class-I myosins contain an
aromatic residue at the positions of Tyr69 and/or Tyr71 (red) in
close contact with the conserved Phe686 (red) in the lever arm
helix. Either a glycine or an alanine is found at the equivalent
position to Phe686 in class-II myosins.
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Figure 4.
Figure 4 A model of chicken skeletal muscle myosin motor core
(white), converter domain and lever arm (yellow) in the
near-rigor state attached to the actin filament (dark gray).
Dictyostelium myosin-II in complex with ADP-BeF[3] with a
modeled extended lever arm in the 'up' or transition state
position is shown in red. The MyoE converter domain and modeled
extended lever arm (cyan) is in an  30°
higher position.
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The above figures are
reprinted
from an Open Access publication published by Macmillan Publishers Ltd:
EMBO J
(2002,
21,
2517-2525)
copyright 2002.
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