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PDBsum entry 1n2d
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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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Structure of the light chain-Binding domain of myosin V.
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Authors
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M.Terrak,
G.Rebowski,
R.C.Lu,
Z.Grabarek,
R.Dominguez.
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Ref.
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Proc Natl Acad Sci U S A, 2005,
102,
12718-12723.
[DOI no: ]
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PubMed id
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Abstract
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Myosin V is a double-headed molecular motor involved in organelle transport. Two
distinctive features of this motor, processivity and the ability to take
extended linear steps of approximately 36 nm along the actin helical track,
depend on its unusually long light chain-binding domain (LCBD). The LCBD of
myosin V consists of six tandem IQ motifs, which constitute the binding sites
for calmodulin (CaM) and CaM-like light chains. Here, we report the 2-A
resolution crystal structure of myosin light chain 1 (Mlc1p) bound to the
IQ2-IQ3 fragment of Myo2p, a myosin V from Saccharomyces cerevisiae. This
structure, combined with FRET distance measurements between probes in various
CaM-IQ complexes, comparative sequence analysis, and the previously determined
structures of Mlc1p-IQ2 and Mlc1p-IQ4, allowed building a model of the LCBD of
myosin V. The IQs of myosin V are distributed into three pairs. There appear to
be specific cooperative interactions between light chains within each IQ pair,
but little or no interaction between pairs, providing flexibility at their
junctions. The second and third IQ pairs each present a light chain, whether CaM
or a CaM-related molecule, bound in a noncanonical extended conformation in
which the N-lobe does not interact with the IQ motif. The resulting free N-lobes
may engage in protein-protein interactions. The extended conformation is
characteristic of the single IQ of myosin VI and is common throughout the myosin
superfamily. The model points to a prominent role of the LCBD in the function,
regulation, and molecular interactions of myosin V.
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Figure 1.
Structure of Mlc1p–IQ2,3. (A) Ribbon diagram representation
of the structure (N-lobes, blue; C-lobes, red; heavy chain,
green). (B) Superimposition of the Mlc1p–IQ2 (gray) and
Mlc1p–IQ3 (colored as in A) portions of the structure. The
side chain of Tyr-843, which forces the opening of the C-lobe in
Mlc1p–IQ3, is shown.
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Figure 3.
Model of the LCBD of myosin V. The light chains, which can be
either CaM or CaM-related molecules such as Mlc1p are colored
cyan (N-lobes) and magenta (C-lobes), and the six-IQ fragment of
the heavy chain is colored green. The LCBD of myosin V can be
conceptually subdivided into three semiindependent pairs of IQ
motifs, with little or no interactions between pairs. The
linkers between neighboring IQ pairs are 14 aa long, whereas the
linkers between IQs in a pair are 12 aa long. An enlargement
illustrates the interaction between light chains in a pair.
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Secondary reference #1
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Title
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Crystallisation, X-Ray characterixation and selenomethionine phasing of mlc1p bound to iq motifs from myosin V
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Authors
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M.Terrak,
L.R.Otterbein,
W.Wu,
L.A.Palecanda,
R.C.Lu,
R.Dominguez.
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Ref.
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acta crystallogr , sect d, 2002,
58,
1882.
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