Solution structure, backbone dynamics and chitin binding of the anti-fungal protein from Streptomyces tendae TU901

Citation
R. Campos-olivas et al., Solution structure, backbone dynamics and chitin binding of the anti-fungal protein from Streptomyces tendae TU901, J MOL BIOL, 308(4), 2001, pp. 765-782
Citations number
52
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Molecular Biology & Genetics
Journal title
JOURNAL OF MOLECULAR BIOLOGY
ISSN journal
0022-2836 → ACNP
Volume
308
Issue
4
Year of publication
2001
Pages
765 - 782
Database
ISI
SICI code
0022-2836(20010511)308:4<765:SSBDAC>2.0.ZU;2-2
Abstract
AFP1 is a recently discovered anti-fungal, chitin-binding protein from Stre ptomyces tendae Tu901. Mature AFP1 comprises 86 residues and exhibits limit ed sequence similarity to the cellulose-binding domains of bacterial cellul ases and xylanases. No similarity to the Cys and Gly-rich domains of plant chitin-binding proteins (e.g. agglutinins, lectins, hevein) is observed. AF P1 is the first chitin-binding protein from a bacterium for which anti-fung al activity was shown. Here, we report the three-dimensional solution struc ture of AFP1, determined by nuclear magnetic resonance spectroscopy. The pr otein contains two antiparallel P-sheets (five and four P-strands each), th at pack against each other in a parallel P-sandwich. This type of architect ure is conserved in the functionally related family IT of cellulose-binding domains, albeit with different connectivity. A similar fold is also observ ed in other unrelated proteins (spore coat protein from Myxococcus xanthus, beta -B-2 and gamma -B crystallins from Bos taurus, canavalin from Jack be an). AFP1 is therefore classified as a new member of the py-crystallin supe rfamily. The dynamics of the protein was characterized by NMR using amide N -15 relaxation and solvent exchange data. We demonstrate that the protein e xhibits an axially sym metric (oblate-like) rotational diffusion tenser who se principal axis coincides to within 15 degrees with that of the inertial tenser. After completion of the present structure of AFP1, an identical fol d was reported for a Streptomyces killer toxin-like protein. Based on seque nce comparisons and clustering of conserved residues on the protein surface for different cellulose and chitin-binding proteins, we postulate a putati ve sugar-binding site for AFP1. The inability of the protein to bind short chitin fragments suggests that certain particular architectural features of the solid chitin surface are crucial for the interaction. (C) 2001 Academi c Press.