 |
PDBsum entry 1afp
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Antifungal protein
|
PDB id
|
|
|
|
1afp
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Nmr solution structure of the antifungal protein from aspergillus giganteus: evidence for cysteine pairing isomerism.
|
|
|
Authors
|
|
R.Campos-Olivas,
M.Bruix,
J.Santoro,
J.Lacadena,
A.Martinez del pozo,
J.G.Gavilanes,
M.Rico.
|
|
|
Ref.
|
|
Biochemistry, 1995,
34,
3009-3021.
|
|
|
PubMed id
|
|
|
|
|
Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
83%.
|
|
|
|
Abstract
|
|
|
The solution structure of the antifungal protein (AFP, 51 residues, 4 disulfide
bridges) from Aspergillus giganteus has been determined by using experimentally
derived interproton distance constraints from nuclear magnetic resonance (NMR)
spectroscopy. Complete sequence-specific proton assignments were obtained at pH
5.0 and 35 degrees C. A set of 834 upper limit distance constraints from nuclear
Overhauser effect measurements was used as input for the calculation of
structures with the program DIANA. An initial family of 40 structures calculated
with no disulfide constraints was used to obtain information about the disulfide
connectivities, which could not be determined by standard biochemical methods.
Three possible disulfide patterns were selected and the corresponding disulfide
constraints applied to generate a family of 20 DIANA conformers for each
pattern. Following energy minimization, the average pairwise RMSD of the 20
conformers of each family is 1.01, 0.89, and 1.01 A for backbone atoms and 1.82,
1.74, and 1.81 A for all heavy atoms. One of these three families contains the
disulfide bridge arrangement actually present in the solution structure of AFP.
Although the three families fulfill the NMR constraints, one of the disulfide
patterns considered (cysteine pairs 7-33, 14-40, 26-49, 28-51) is favored among
the others on the basis of previous chemical studies. It thus probably
corresponds to the actual pattern of disulfide bridges present in the protein,
and the corresponding family represents the solution structure of AFP. The
folding of AFP consists of five antiparallel beta strands connected in a -1, -1,
+3, +1 topology and highly twisted, defining a small and compact beta barrel
stabilized by four internal disulfide bridges. A cationic site formed by up to
three lysine side chains adjacent to a hydrophobic stretch, both at the protein
surface, may constitute a potential binding site for phospholipids which would
be the basis of its biological function. On the other hand, a second, minor form
of AFP has been detected. NMR data, together with results from mass
spectrometry, chemical analysis, and sedimentation equilibrium, suggest that
this species differs from the major form in the pairs of cysteines involved in
the four disulfide bridges.
|
|
|
|
|
|
|
