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PDBsum entry 2pr6
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Flavoprotein, signaling protein
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PDB id
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2pr6
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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 basis for light-Dependent signaling in the dimeric lov domain of the photosensor ytva.
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Authors
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A.Möglich,
K.Moffat.
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Ref.
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J Mol Biol, 2007,
373,
112-126.
[DOI no: ]
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PubMed id
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Abstract
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The photosensor YtvA binds flavin mononucleotide and regulates the general
stress reaction in Bacillus subtilis in response to blue light illumination. It
belongs to the family of light-oxygen-voltage (LOV) proteins that were first
described in plant phototropins and form a subgroup of the Per-Arnt-Sim (PAS)
superfamily. Here, we report the three-dimensional structure of the LOV domain
of YtvA in its dark and light states. The protein assumes the global fold common
to all PAS domains and dimerizes via a hydrophobic interface. Directly
C-terminal to the core of the LOV domain, an alpha-helix extends into the
solvent. Light absorption causes formation of a covalent bond between a
conserved cysteine residue and atom C(4a) of the FMN ring, which triggers
rearrangements throughout the LOV domain. Concomitantly, in the dark and light
structures, the two subunits of the dimeric protein rotate relative to each
other by 5 degrees . This small quaternary structural change is presumably a
component of the mechanism by which the activity of YtvA is regulated in
response to light. In terms of both structure and signaling mechanism, YtvA
differs from plant phototropins and more closely resembles prokaryotic
heme-binding PAS domains.
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Figure 2.
Figure 2. (a) Crystal structure of the head-to-head dimer of
YtvA-LOV in its ground (dark) state. The FMN cofactors are
highlighted in stick representation and the secondary structure
elements (blue and light brown) are labeled. Within the crystal,
the two C-terminal Jα helices form intermolecular contacts with
the corresponding Jα' helices of symmetry-related molecules
(white). For clarity, only the Jα helices of symmetry-related
molecules are shown. (b) The dimer interface. Hydrophobic
residues V25, V27, I29, Y41, M111, I113, Y118, V120, and I122
located on the outside of the β-sheet in strands Aβ, Bβ, Hβ
and Iβ form intermolecular contacts between the two monomers.
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Figure 3.
Figure 3. Comparison of the FMN-binding site in the dark
state structures of (a) YtvA-LOV, (b) Chlamydomonas phot1 LOV1
and (c) Adiantum phy3 LOV2. Carbon atoms are shown in black,
nitrogen atoms in blue, oxygen atoms in red, sulfur in yellow
and phosphorus in magenta. Water molecules are depicted as red
spheres. Broken green lines indicate hydrogen bonds or
salt-bridges. The hydrogen bond network coordinating the FMN
ring is highly conserved between the various LOV domains,
whereas there is some variability in the hydrophobic residues
lining the flavin ring. The key cysteine residue may adopt two
conformations in the dark state, denoted a and b.
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The above figures are
reprinted
from an Open Access publication published by Elsevier:
J Mol Biol
(2007,
373,
112-126)
copyright 2007.
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