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PDBsum entry 3edc
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Transcription
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PDB id
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3edc
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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 a 1.6-Hexanediol bound tetrameric form of escherichia coli lac-Repressor refined to 2.1 a resolution.
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Authors
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K.A.Stenberg,
M.Vihinen.
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Ref.
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Proteins, 2008,
75,
748-759.
[DOI no: ]
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PubMed id
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Abstract
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We report the structure of a novel tetrameric form of the lactose repressor
(LacI) protein from Escherichia coli refined to 2.1 A resolution. The tetramer
is bound to 1.6-hexanediol present in the crystallization solution and the final
R(free) for the structure is 0.201. The structure confirms previously reported
structures on the monomer level. However, the tetramer is much more densely
packed. This adds a new level of complexity to the interpretation of mutational
effects and challenges details in the current model for LacI function. Several
amino acids, previously associated with changes in function but unexplained at
the structural level, appear in a new structural context in this tetramer which
provides new implications for their function. Proteins 2009. (c) 2008
Wiley-Liss, Inc.
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Figure 1.
Figure 1. Comparison of the overall protein part of LacI
tetramer structures from an identical viewpoint with respect to
monomer A (green). The dimer-dimer interface and distances
between monomers vary strongly due to the rotation of the
CD-dimer. (a) our model, (b) IPTG and ethyl mercury-bound (PDB
code 1TLF), (c) apoform (1LBI), (d) IPTG-bound (1LBH) and (e)
DNA-bound (1LBG). The distances between the C  -atoms
of B102 and D102 (in ångströms) are indicated.
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Figure 2.
Figure 2. Structure of the closed tetramer. (a) Surface of the
complete tetramer. The viewpoint is identical to that of Figure
1(a), green, monomer A; red, monomer B; magenta, monomer C;
yellow, monomer D. It is quite evident that the V-cleft is
completely closed. (b) Stereo view of the top of the closed
dimer-dimer interface. (c) Stereo view of the amino acids at the
bottom of the Vcleft between monomers B and D. The KRK-motif of
monomer D and some interaction distances are shown under a
surface representation. (d) The structure and electron density
around Hez-A. The density is from a CNS composite omit map[36],
contoured at 1.25  ,
carve = 1.6 Å.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2008,
75,
748-759)
copyright 2008.
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