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PDBsum entry 1i2u
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Antifungal protein
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PDB id
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1i2u
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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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Solution structures of the antifungal heliomicin and a selected variant with both antibacterial and antifungal activities.
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Authors
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M.Lamberty,
A.Caille,
C.Landon,
S.Tassin-Moindrot,
C.Hetru,
P.Bulet,
F.Vovelle.
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Ref.
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Biochemistry, 2001,
40,
11995-12003.
[DOI no: ]
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PubMed id
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Abstract
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In response to an experimental infection, the lepidopteran Heliothis virescens
produces an antifungal protein named heliomicin. Heliomicin displays sequence
similarities with antifungal plant defensins and antibacterial or antifungal
insect defensins. To gain information about the structural elements required for
either antifungal or antibacterial activity, heliomicin and selected
point-mutated variants were expressed in yeast as fusion proteins. The effects
of mutations, defined by comparing the primary structure of heliomicin with the
sequences of members of the insect defensin family, were analyzed using
antibacterial and antifungal assays. One of the variants shows significant
activity against Gram-positive bacteria while remaining efficient against fungi.
The three-dimensional structures of this variant and of the wild-type protein
were determined by two-dimensional (1)H NMR to establish a correlation between
structure and antibacterial or antifungal activity. Wild-type and mutated
heliomicins adopt a similar scaffold, including the so-called
cysteine-stabilized alphabeta motif. A comparison of their structures with other
defensin-type molecules indicates that common hydrophobic characteristics can be
assigned to all the antifungal proteins. A comparative analysis of various
structural features of heliomicin mutant and of antibacterial defensins enables
common properties to be assessed, which will help to design new mutants with
increased antibacterial activity.
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Secondary reference #1
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Title
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Insect immunity. Isolation from the lepidopteran heliothis virescens of a novel insect defensin with potent antifungal activity.
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Authors
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M.Lamberty,
S.Ades,
S.Uttenweiler-Joseph,
G.Brookhart,
D.Bushey,
J.A.Hoffmann,
P.Bulet.
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Ref.
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J Biol Chem, 1999,
274,
9320-9326.
[DOI no: ]
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PubMed id
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Figure 1.
Fig. 1. First reversed-phase HPLC separation of immune
hemolymph of H. virescens. The 40% acetonitrile fraction
obtained after prepurification by solid phase extraction was
analyzed on an Aquapore RP-300 C [8] column. Elution was
performed with a linear gradient (dotted line) of acetonitrile
in acidified water. Absorbance was monitored at 225 nm (solid
line). Antimicrobial activities were detected by liquid growth
inhibition assays against M. luteus, (white column), E. coli
(dotted column), and N. crassa (black column). The inset shows
the final purification of fraction A, which contains the active
antifungal compound.
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Figure 4.
Fig. 4. Sequence comparison of heliomicin with other
antimicrobial peptides from insects and plants. Heliomicin was
compared (i) to two antifungal peptides (drosomycin from D.
melanogaster and Rs-AFP1 from the Brassicaceae R. sativus) and
(ii) to some of the most representative insect defensins.
Identical amino acids and conservative replacements are shown in
gray boxes. Bars indicate gaps to optimize the alignments.
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The above figures are
reproduced from the cited reference
with permission from the ASBMB
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