PDBsum entry 1afp

Antifungal protein

PDB id: 1afp

Contents

Protein chain

51 a.a.

PDB id:

1afp

Name:

Antifungal protein

Title:

Solution structure of the antifungal protein from aspergillus giganteus. Evidence for disulphide configurational isomerism

Structure:

Antifungal protein from aspergillus giganteus. Chain: a. Engineered: yes

Source:

Aspergillus giganteus. Organism_taxid: 5060

NMR struc:

40 models

Authors:

R.Campos-Olivas,M.Bruix,J.Santoro,J.Lacadena,A.M.Del Pozo, J.G.Gavilanes,M.Rico

Key ref:

R.Campos-Olivas et al. (1995). NMR solution structure of the antifungal protein from Aspergillus giganteus: evidence for cysteine pairing isomerism. Biochemistry, 34, 3009-3021. PubMed id: 7893713

Date:

11-Nov-94 Release date: 07-Feb-95

Protein chain

P17737  (AFP_ASPGI) -  Antifungal protein from Aspergillus giganteus

Seq: 94 a.a.

Struc: 51 a.a.

Enzyme reactions

• Enzyme class: E.C.?

Biochemistry 34:3009-3021 (1995)

PubMed id: 7893713

NMR solution structure of the antifungal protein from Aspergillus giganteus: evidence for cysteine pairing isomerism.

R.Campos-Olivas, M.Bruix, J.Santoro, J.Lacadena, A.Martinez del Pozo, J.G.Gavilanes, M.Rico.

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.