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PDBsum entry 1isp
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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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Alternate conformations observed in catalytic serine of bacillus subtilis lipase determined at 1.3 a resolution.
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Authors
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K.Kawasaki,
H.Kondo,
M.Suzuki,
S.Ohgiya,
S.Tsuda.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2002,
58,
1168-1174.
[DOI no: ]
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PubMed id
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Abstract
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Bacillus subtilis extracellular lipase (BsL) has an exceptionally low molecular
weight (19.4 kDa) for a member of the lipase family. A crystallographic study
was performed on BsL in order to design and produce mutant BsL that will be more
suitable for industrial uses based on analysis of the three-dimensional
structure. Recently, the crystal structure of BsL has been determined at 1.5 A
resolution [van Pouderoyen et al. (2001). J. Mol. Biol. 309, 215-226]. In the
present study, a new crystal form of BsL which provides diffraction data to
higher resolution was obtained and its structure was determined at 1.3 A using
the MAD method. It was found that the active-site residue Ser77 has alternate
side-chain conformations. The O(gamma) atom of the first conformer forms a
hydrogen bond to the N(epsilon) atom of His155, a member of the catalytic triad.
In contrast, the second conformer is constructed with a hydrogen bond to the
side-chain atom of the adjacent His76. These two conformers presumably
correspond to the active and inactive states, respectively. Similar alternate
conformations in the catalytic serine residue have been observed in Fusarium
solani cutinase determined at 1.0 A resolution and Penicillium purpurogenum
acetylxylan esterase at 0.9 A resolution. In addition, a glycerol molecule,
which was used as a cryoprotectant, is found to be located in the active site.
On the basis of these results, a model for substrate binding in the
reaction-intermediate state of BsL is proposed.
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Figure 1.
Figure 1 A schematic drawing of BsL produced with MOLSCRIPT
(Kraulis, 1991[Kraulis, P. J. (1991). J. Appl. Cryst. 24,
946-950.]) and RASTER3D (Merritt & Bacon, 1997[Merritt, E. A. &
Bacon, D. J. (1997). Methods. Enzymol. 277, 505-524.]).
Secondary structures are labelled (  1-
6,
 1-
5).
The side chains of the catalytic triad (Ser77, Asp133 and
His156) are represented in ball-and-stick. The N- and C-termini
are denoted N and C, respectively.
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Figure 4.
Figure 4 Omit map for the glycerol molecule at the active site.
 [A]-weighted
2F[o] - F[c] and F[o] - F[c] maps are drawn in blue and red,
respectively. Each map is contoured at 2 .
One hydroxyl O atom of the glycerol is labelled O1.
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(2002,
58,
1168-1174)
copyright 2002.
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