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PDBsum entry 3tu5
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Structural protein/actin-binding protein
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PDB id
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3tu5
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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 states and dynamics of the d-Loop in actin.
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Authors
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Z.A.Durer,
D.S.Kudryashov,
M.R.Sawaya,
C.Altenbach,
W.Hubbell,
E.Reisler.
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Ref.
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Biophys J, 2012,
103,
930-939.
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PubMed id
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Abstract
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Conformational changes induced by ATP hydrolysis on actin are involved in the
regulation of complex actin networks. Previous structural and biochemical data
implicate the DNase I binding loop (D-loop) of actin in such
nucleotide-dependent changes. Here, we investigated the structural and
conformational states of the D-loop (in solution) using cysteine scanning
mutagenesis and site-directed labeling. The reactivity of D-loop cysteine
mutants toward acrylodan and the mobility of spin labels on these mutants do not
show patterns of an α-helical structure in monomeric and filamentous actin,
irrespective of the bound nucleotide. Upon transition from monomeric to
filamentous actin, acrylodan emission spectra and electron paramagnetic
resonance line shapes of labeled mutants are blue-shifted and more immobilized,
respectively, with the central residues (residues 43-47) showing the most
drastic changes. Moreover, complex electron paramagnetic resonance line shapes
of spin-labeled mutants suggest several conformational states of the D-loop.
Together with a new (to our knowledge) actin crystal structure that reveals the
D-loop in a unique hairpin conformation, our data suggest that the D-loop
equilibrates in F-actin among different conformational states irrespective of
the nucleotide state of actin.
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