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PDBsum entry 1b5f
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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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Crystal structure of cardosin a, A glycosylated and arg-Gly-Asp-Containing aspartic proteinase from the flowers of cynara cardunculus l.
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Authors
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C.Frazão,
I.Bento,
J.Costa,
C.M.Soares,
P.Veríssimo,
C.Faro,
E.Pires,
J.Cooper,
M.A.Carrondo.
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Ref.
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J Biol Chem, 1999,
274,
27694-27701.
[DOI no: ]
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PubMed id
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Abstract
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Aspartic proteinases (AP) have been widely studied within the living world, but
so far no plant AP have been structurally characterized. The refined cardosin A
crystallographic structure includes two molecules, built up by two glycosylated
peptide chains (31 and 15 kDa each). The fold of cardosin A is typical within
the AP family. The glycosyl content is described by 19 sugar rings attached to
Asn-67 and Asn-257. They are localized on the molecular surface away from the
conserved active site and show a new glycan of the plant complex type. A
hydrogen bond between Gln-126 and Manbeta4 renders the monosaccharide oxygen O-2
sterically inaccessible to accept a xylosyl residue, therefore explaining the
new type of the identified plant glycan. The Arg-Gly-Asp sequence, which has
been shown to be involved in recognition of a putative cardosin A receptor, was
found in a loop between two beta-strands on the molecular surface opposite the
active site cleft. Based on the crystal structure, a possible mechanism whereby
cardosin A might be orientated at the cell surface of the style to interact with
its putative receptor from pollen is proposed. The biological implications of
these findings are also discussed.
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Figure 1.
Fig. 1. A, cartoon representation (49, 50) of the two
cardosin A molecules in the a.u. They face each other through an
extensive area, although the actual molecule to molecule
contacts are relatively few. The two N-linked glycans are
represented as ball-and-sticks with side chains of linking Asn67
and Asn257. The active site aspartate side chains, as well as
those from a putative molecular adhesion RGD motif (12) (Arg176,
Gly177, and Asp178) are also depicted as ball-and-stick
representation. The missing PSI domain is indicated near its
chain termini. B, accessible surface representation (51) of the
contact regions between the two cardosin molecules in the a.u.
Molecule 1 (left) and 2 (right) facing surfaces are represented
after a 180° rotation around a vertical axis of one of the
molecules. The contacts between the two molecules produce a
decrease of the local solvent-accessible area represented in
blue with the rest of the surface in white. The contacts are
highly delocalized over the intermolecular surfaces and are
spread over a wide region.
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Figure 3.
Fig. 3. Sub-site specificity mapping of cardosin A.
Schematic representation (21) of a  -casein
chain fragment, with peptide scissile bond Phe^105  Met106,
where milk clotting is initiated in cheese production. Cardosin
A residues within 4.0 Å of the docked -casein
fragment are listed and grouped at their sub-sites (Sn and S'n).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(1999,
274,
27694-27701)
copyright 1999.
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Secondary reference #1
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Title
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Crystallization and preliminary X-Ray crystallographic studies of the plant aspartic proteinase cardosin a.
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Authors
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I.Bento,
C.Frazão,
R.Coelho,
K.Wilson,
Z.Dauter,
M.A.Carrondo.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 1998,
54,
991-993.
[DOI no: ]
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PubMed id
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Secondary reference #2
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Title
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Crystallisation, Structure solution, And initial refinement of plant cardosin-A.
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Authors
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I.Bento,
R.Coelho,
C.Frazão,
J.Costa,
C.Faro,
P.Veríssimo,
E.Pires,
J.Cooper,
Z.Dauter,
K.Wilson,
M.A.Carrondo.
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Ref.
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Adv Exp Med Biol, 1998,
436,
445-452.
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PubMed id
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