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PDBsum entry 1e8q
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Cellulose docking domain
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PDB id
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1e8q
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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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Characterization of a cellulosome dockerin domain from the anaerobic fungus piromyces equi.
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Authors
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S.Raghothama,
R.Y.Eberhardt,
P.Simpson,
D.Wigelsworth,
P.White,
G.P.Hazlewood,
T.Nagy,
H.J.Gilbert,
M.P.Williamson.
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Ref.
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Nat Struct Biol, 2001,
8,
775-778.
[DOI no: ]
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PubMed id
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Abstract
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The recycling of photosynthetically fixed carbon in plant cell walls is a key
microbial process. In anaerobes, the degradation is carried out by a high
molecular weight multifunctional complex termed the cellulosome. This consists
of a number of independent enzyme components, each of which contains a conserved
dockerin domain, which functions to bind the enzyme to a cohesin domain within
the protein scaffoldin protein. Here we describe the first three-dimensional
structure of a fungal dockerin, the N-terminal dockerin of Cel45A from the
anaerobic fungus Piromyces equi. The structure contains a novel fold of 42
residues. The ligand binding site consists of residues Trp 35, Tyr 8 and Asp 23,
which are conserved in all fungal dockerins. The binding site is on the opposite
side of the N- and C-termini of the molecule, implying that tandem dockerin
domains, seen in the majority of anaerobic fungal plant cell wall degrading
enzymes, could present multiple simultaneous binding sites and, therefore,
permit tailoring of binding to catalytic demands.
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Figure 2.
Figure 2. Solution structure of the P. equi dockerin. a,
Stereo view of the ensemble of 34 structures, colored from red
at the N-terminus to blue at the C-terminus. b, Stereo
MOLSCRIPT27 diagram of the dockerin structure, showing the
locations of disulfide bridges and the binding site residues
discussed in the text. The protein present in the sample
consisted of 52 residues -- that is, the 38-residue 'core'
sequence that is highly conserved in fungal dockerins, plus all
12 residues C-terminal of the core sequence prior to the start
of the second dockerin domain, and two N-terminal residues from
the GST-tag. The figure shows only the ordered residues -2 -44.
c, Surface of the protein, in the same orientation as (b). Side
chains of residues Tyr 8 and Trp 35 are in purple, and Asp 23 in
light lilac. Acidic residues are in red, basic in dark blue and
hydrophobic in yellow.
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Figure 3.
Figure 3. 15N T[2] values for backbone nitrogens. Values (ms)
are plotted against residue number.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2001,
8,
775-778)
copyright 2001.
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