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PDBsum entry 2zs6
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* Residue conservation analysis
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Enzyme class:
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Chains A, B:
E.C.?
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DOI no:
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J Mol Biol
385:1193-1206
(2009)
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PubMed id:
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Crystal Structure of the HA3 Subcomponent of Clostridium botulinum Type C Progenitor Toxin.
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T.Nakamura,
M.Kotani,
T.Tonozuka,
A.Ide,
K.Oguma,
A.Nishikawa.
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ABSTRACT
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The Clostridium botulinum type C 16S progenitor toxin contains a neurotoxin and
several nontoxic components, designated nontoxic nonhemagglutinin (HA), HA1
(HA-33), HA2 (HA-17), HA3a (HA-22-23), and HA3b (HA-53). The HA3b subcomponent
seems to play an important role cooperatively with HA1 in the internalization of
the toxin by gastrointestinal epithelial cells via binding of these
subcomponents to specific oligosaccharides. In this study, we investigated the
sugar-binding specificity of the HA3b subcomponent using recombinant protein
fused to glutathione S-transferase and determined the three-dimensional
structure of the HA3a-HA3b complex based on X-ray crystallography. The crystal
structure was determined at a resolution of 2.6 A. HA3b contains three domains,
domains I to III, and the structure of domain I resembles HA3a. In crystal
packing, three HA3a-HA3b molecules are assembled to form a three-leaved
propeller-like structure. The three HA3b domain I and three HA3a alternate,
forming a trimer of dimers. In a database search, no proteins with high
structural homology to any of the domains (Z score >10) were found.
Especially, HA3a and HA3b domain I, mainly composed of beta-sheets, reveal a
unique fold. In binding assays, HA3b bound sialic acid with high affinity, but
did not bind galactose, N-acetylgalactosamine, or N-acetylglucosamine. The
electron density of liganded N-acetylneuraminic acid was determined by crystal
soaking. In the sugar-complex structure, the N-acetylneuraminic acid-binding
site was located in the cleft formed between domains II and III of HA3b. This
report provides the first determination of the three-dimensional structure of
the HA3a-HA3b complex and its sialic acid binding site. Our results will provide
useful information for elucidating the mechanism of assembly of the C16S toxin
and for understanding the interactions with oligosaccharides on epithelial cells
and internalization of the botulinum toxin complex.
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Selected figure(s)
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Figure 1.
Fig. 1. Three-dimensional structure of HA3. (a) The trimer
structure of HA3. In Mol-A, HA3a and the domains of HA3b are
colored green, purple, yellow, and magenta. Two other HA3a and
HA3b molecules, Mol-B and Mol-C, are shown in light blue and
olive, respectively. (b) Wall-eye stereo view of the overall
structure of HA3 as a complex of HA3a and HA3b. There is one
molecule in an asymmetric unit. The structure of HA3 consists of
two components, HA3a (green) and HA3b, and HA3b is composed of
three domains, domain I (purple), domain II (yellow), and domain
III (magenta). The C-terminal residue of HA3a and the N-terminal
residue of HA3b domain I are indicated by red triangles. The
sugar-binding position located on HA3b domain III is shown as a
purple circle.
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Figure 2.
Fig. 2. Schematic representation of HA3a and each domain of
HA3b. β-Strands of each domain are indicated with arrowheads
and numbered. The helices are illustrated as black columns and
labeled alphabetically. Domain I of HA3a and HA3b are
structurally similar to each other. However, HA3b domain I
contains the Pro-loop and the short β-strands, βI and βII,
which run between the β6–β6′ and β7–β7′ strands, and
these structural features differ from HA3a. HA3b domain II and
domain III form similar structural compositions, jelly-roll-like
folds.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2009,
385,
1193-1206)
copyright 2009.
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Figures were
selected
by an automated process.
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Literature references that cite this PDB file's key reference
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PubMed id
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Reference
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H.Ito,
Y.Sagane,
K.Miyata,
K.Inui,
T.Matsuo,
R.Horiuchi,
T.Ikeda,
T.Suzuki,
K.Hasegawa,
H.Kouguchi,
K.Oguma,
K.Niwa,
T.Ohyama,
and
T.Watanabe
(2011).
HA-33 facilitates transport of the serotype D botulinum toxin across a rat intestinal epithelial cell monolayer.
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FEMS Immunol Med Microbiol,
61,
323-331.
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P.Sampathkumar,
S.A.Ozyurt,
S.A.Miller,
K.T.Bain,
M.E.Rutter,
T.Gheyi,
B.Abrams,
Y.Wang,
S.Atwell,
J.G.Luz,
D.A.Thompson,
S.R.Wasserman,
J.S.Emtage,
E.C.Park,
C.Rongo,
Y.Jin,
R.L.Klemke,
J.M.Sauder,
and
S.K.Burley
(2010).
Structures of PHR domains from Mus musculus Phr1 (Mycbp2) explain the loss-of-function mutation (Gly1092-->Glu) of the C. elegans ortholog RPM-1.
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J Mol Biol,
397,
883-892.
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PDB codes:
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Y.Fujinaga
(2010).
Interaction of botulinum toxin with the epithelial barrier.
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J Biomed Biotechnol,
2010,
974943.
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The most recent references are shown first.
Citation data come partly from CiteXplore and partly
from an automated harvesting procedure. Note that this is likely to be
only a partial list as not all journals are covered by
either method. However, we are continually building up the citation data
so more and more references will be included with time.
Where a reference describes a PDB structure, the PDB
codes are
shown on the right.
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Links
