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PDBsum entry 2w3q
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References listed in PDB file
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Key reference
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Title
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Structure and inhibition of the co(2)-Sensing carbonic anhydrase can2 from the pathogenic fungus cryptococcus neoformans.
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Authors
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C.Schlicker,
R.A.Hall,
D.Vullo,
S.Middelhaufe,
M.Gertz,
C.T.Supuran,
F.A.Mühlschlegel,
C.Steegborn.
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Ref.
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J Mol Biol, 2009,
385,
1207-1220.
[DOI no: ]
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PubMed id
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Abstract
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In the pathogenic fungus Cryptococcus neoformans, a CO(2)-sensing system is
essential for survival in the natural environment ( approximately 0.03% CO(2))
and mediates the switch to virulent growth in the human host ( approximately 5%
CO(2)). This system is composed of the carbonic anhydrase (CA) Can2, which
catalyzes formation of bicarbonate, and the fungal, bicarbonate-stimulated
adenylyl cyclase Cac1. The critical role of these enzymes for fungal metabolism
and pathogenesis identifies them as targets for antifungal drugs. Here, we prove
functional similarity of Can2 to the CA Nce103 from Candida albicans and
describe its biochemical and structural characterization. The crystal structure
of Can2 reveals that the enzyme belongs to the "plant-type" beta-CAs but carries
a unique N-terminal extension that can interact with the active-site entrance of
the dimer. We further tested a panel of compounds, identifying nanomolar Can2
inhibitors, and present the structure of a Can2 complex with the inhibitor and
product analog acetate, revealing insights into interactions with physiological
ligands and inhibitors.
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Figure 3.
Fig. 3. Active site and inhibition of Can2. (a) Active site
of Can2 with electron density contoured at 1.0 σ. Coordination
of the active-site Zn^2+ by Cys68, His124, Cys127, and a water
molecule is indicated by black broken lines, and the hydrogen
bond from the water molecule to Asp70 is colored orange. (b)
Overlay of the active sites of Can2 and the plant-type β-CAs of
E. coli (yellow) and P. sativum (dark red) and the Cab-type
β-CAs of M. thermoautotrophicum (green) and M. tuberculosis
Rv1284 (gray). The Zn^2+ ions are shown as orange spheres, and
the water molecules are colored according to the organism. (c)
Chemical structure of the most potent inhibitors identified for
Can2, AAZ, and benzolamide. (d) Detrimental effect of the Can2
inhibitors AAZ and benzolamide on the growth of the C. albicans
Nce103 deletion mutant expressing CAN2 (RH1). RH1 was spotted
onto YNB agar at 1 × 10^5, 1 × 10^4, and 1 ×
10^3 cells/ml in the presence of (i) 4% DMSO and 3 mM
benzolamide for 96 h or (ii) 4% DMSO and 3 mM AAZ for 72 h.
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Figure 4.
Fig. 4. Can2 complex with the product analog acetate. (a)
Overall structure of the Can2/acetate complex (monomer C, gray)
overlaid with the structure of uncomplexed Can2 (blue). The
Zn^2+ ions are shown as orange spheres. (b) Overlay of the
active sites of the Can2/acetate complex and the Can2 structure
with a bound water molecule (blue: Can2/water structure;
aquamarine: Can2/acetate monomer A; cyan: Can2/acetate monomer
B; gray: Can2/acetate monomer C). (c) Modeling of a
Can2/benzolamide complex. Residues coordinating the active-site
ion, restricting the space available to the inhibitor, or
reachable for the inhibitor moieties are labeled.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2009,
385,
1207-1220)
copyright 2009.
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