{PDOC00025} {PS00026; CHIT_BIND_I_1} {PS50941; CHIT_BIND_I_2} {BEGIN} ****************************************************** * Chitin-binding type-1 domain signature and profile * ****************************************************** Many plants respond to pathogenic attack by producing defense proteins that are capable of reversible binding to chitin, an N-acetylglucosamine polysaccharide present in the cell wall of fungi and the exoskeleton of insects. Most of these chitin-binding proteins include a common structural motif of 30 to 43 residues organized around a conserved four-disulfide core, known as the chitin-binding domain type-1 [1]. The topological arrangement of the four disulfide bonds is shown in the following figure: +-------------+ +----|------+ | | | | | xxCgxxxxxxxCxxxxCCsxxgxCgxxxxxCxxxCxxxxC | ******|************* | | | | +----+ +--------------+ 'C': conserved cysteine involved in a disulfide bond. '*': position of the pattern. The structure of several chitin-binding domain type-1 have been solved, (see for example ) [2]. The chitin-binding site is localized in a beta-hairpin loop formed by the second disulfide bridge. Conserved serine and aromatic residues associated with the hairpin-loop are essential for the chitin-binding activity [3]. The chitin-binding domain type-1 displays some structural similarities with the chitin-binding domain type-2 (see ). Some of the proteins containing a chitin-binding domain type-1 are listed below: - A number of non-leguminous plant lectins. The best characterized of these lectins are the three highly homologous wheat germ agglutinins (WGA-1, 2 and 3). WGA is an N-acetylglucosamine/N-acetylneuraminic acid binding lectin which structurally consists of a fourfold repetition of the 43 amino acid domain. The same type of structure is found in a barley root-specific lectin as well as a rice lectin. - Plants endochitinases (EC 3.2.1.14) from class IA (see ). Endochitinases are enzymes that catalyze the hydrolysis of the beta-1,4 linkages of N-acetyl glucosamine polymers of chitin. Plant chitinases function as a defense against chitin containing fungal pathogens. Class IA chitinases generally contain one copy of the chitin-binding domain at their N-terminal extremity. An exception is agglutinin/chitinase [4] from the stinging nettle Urtica dioica which contains two copies of the domain. - Hevein, a wound-induced protein found in the latex of rubber trees. - Win1 and win2, two wound-induced proteins from potato. - Kluyveromyces lactis killer toxin alpha subunit [5]. The toxin encoded by the linear plasmid pGKL1 is composed of three subunits: alpha, beta, and gamma. The gamma subunit harbors toxin activity and inhibits growth of sensitive yeast strains in the G1 phase of the cell cycle; the alpha subunit, which is proteolytically processed from a larger precursor that also contains the beta subunit, is a chitinase (see ). The profile we developed covers the whole domain. -Consensus pattern: C-x(4,5)-C-C-S-x(2)-G-x-C-G-x(3,4)-[FYW]-C [The 5 C's are involved in disulfide bonds] -Sequences known to belong to this class detected by the profile: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Sequences known to belong to this class detected by the profile: ALL. -Other sequence(s) detected in Swiss-Prot: NONE. -Note: Hevein is a strong allergen which is implied in the allergy to natural rubber latex (NRL). NLR can be associated to hypersensitivity to some plant-derived foods (latex-fruit syndrome). An increasing number of plant sources, such as avocado, banana, chestnut, kiwi, peach, tomato, potato and bell pepper, have been associated with this syndrome. Several papers [6,7] have shown that allergen cross-reactivity is due to IgE antibodies that recognize structurally similar epitopes on different proteins that are closely related. One of these family is plant defence proteins class I chitinase containing a type-1 chitin-binding domain. -Last update: December 2004 / Pattern and text revised. [ 1] Wright H.T., Sandrasegaram G., Wright C.S. "Evolution of a family of N-acetylglucosamine binding proteins containing the disulfide-rich domain of wheat germ agglutinin." J. Mol. Evol. 33:283-294(1991). PubMed=1757999 [ 2] Andersen N.H., Cao B., Rodriguez-Romero A., Arreguin B. "Hevein: NMR assignment and assessment of solution-state folding for the agglutinin-toxin motif." Biochemistry 32:1407-1422(1993). PubMed=8431421 [ 3] Asensio J.L., Canada F.J., Siebert H.C., Laynez J., Poveda A., Nieto P.M., Soedjanaamadja U.M., Gabius H.J., Jimenez-Barbero J. "Structural basis for chitin recognition by defense proteins: GlcNAc residues are bound in a multivalent fashion by extended binding sites in hevein domains." Chem. Biol. 7:529-543(2000). PubMed=10903932 [ 4] Lerner D.R., Raikhel N.V. "The gene for stinging nettle lectin (Urtica dioica agglutinin) encodes both a lectin and a chitinase." J. Biol. Chem. 267:11085-11091(1992). PubMed=1375935 [ 5] Butler A.R., O'Donnell R.W., Martin V.J., Gooday G.W., Stark M.J.R. "Kluyveromyces lactis toxin has an essential chitinase activity." Eur. J. Biochem. 199:483-488(1991). PubMed=2070799 [ 6] Sowka S., Hsieh L.S., Krebitz M., Akasawa A., Martin B.M., Starrett D., Peterbauer C.K., Scheiner O., Breiteneder H. "Identification and cloning of prs a 1, a 32-kDa endochitinase and major allergen of avocado, and its expression in the yeast Pichia pastoris." J. Biol. Chem. 273:28091-28097(1998). PubMed=9774427 [ 7] Wagner S., Breiteneder H. "The latex-fruit syndrome." Biochem. Soc. Trans. 30:935-940(2002). PubMed=12440950; -------------------------------------------------------------------------------- PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see https://prosite.expasy.org/prosite_license.html -------------------------------------------------------------------------------- {END}