The X8 domain, which may be involved in carbohydrate binding, is found in an Olive pollen antigen as well as at the C terminus of family 17 glycosyl hydrolases. It contains 6 conserved cysteine residues which presumably form three disulfide bridges.
The X8 domain (PUBMED:11115868) contains 6 conserved cysteine residues that presumably form three disulphide bridges. The domain is found in an Olive pollen allergen (PUBMED:15004167) as well as at the C terminus of family 17 glycosyl hydrolases (PUBMED:11554480). This domain may be involved in carbohydrate binding.
Family alignment:
There are 344
X8 domains in 327 proteins in SMART's nrdb database.
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Evolution (species in which this domain is found)
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This tree shows only several representative species. The complete taxonomic breakdown of all proteins with X8 domain is also avaliable.
A major allergen from pollen defines a novel family of plant proteins and shows intra- and interspecies [correction of interspecie] cross-reactivity.
J Immunol. 2004; 172: 3644-51
Display abstract
Olive tree (Olea europaea) pollen is a main cause of allergy associated with extensive areas of Europe and North America. Ole e 10, a small (10.8 kDa) and acidic (pI 5.8) protein, has been identified as a major allergen from the olive pollen, isolated, and characterized. Circular dichroism analysis gave 17% alpha helix, 33% beta sheet, and 21% beta turn for its secondary structure. Based on amino acid sequences of tryptic peptides, the protein was cloned and sequenced. The allergen consists of a single polypeptide chain of 102 aa, with a signal peptide of 21 residues. Ole e 10 showed homology with the C-terminal domain of another olive allergen, Ole e 9 (1,3-beta-glucanase, 53% identity), with deduced sequences from Arabidopsis thaliana genes (42-46% identity) and with polypeptide segments (Cys boxes) of proteins involved in yeast development (Epd1/Gas-1p/Phr2 families; 42-43% similarity). Ole e 10 showed 55% prevalence for olive-allergic patients and exhibited an IgE response dependent on its conformation. Remarkable IgE cross-reactivity was detected with Ole e 9, but no correlation was observed between the individual IgE responses to both allergens. Ole e 10 shares IgE B cell epitopes with proteins from Oleaceae, Gramineae, Betulaceae, Chenopodiaceae, Cupressaceae, Ambrosia, and Parietaria pollens, latex, and vegetable foods, such as tomato, kiwi, potato, and peach. These data indicate that Ole e 10 is a new pan-allergenic plant protein that shows notable intra- and interspecie IgE cross-reactivity and is a powerful candidate to be involved in pollen-latex-fruit syndrome.
A census of carbohydrate-active enzymes in the genome of Arabidopsis thaliana.
Plant Mol Biol. 2001; 47: 55-72
Display abstract
The synthesis, modification, and breakdown of carbohydrates is one of the most fundamentally important reactions in nature. The structural and functional diversity of glycosides is mirrored by a vast array of enzymes involved in their synthesis (glycosyltransferases), modification (carbohydrate esterases) and breakdown (glycoside hydrolases and polysaccharide lyases). The importance of these processes is reflected in the dedication of 1-2% of an organism's genes to glycoside hydrolases and glycosyltransferases alone. In plants, these processes are of particular importance for cell-wall synthesis and expansion. starch metabolism, defence against pathogens, symbiosis and signalling. Here we present an analysis of over 730 open reading frames representing the two main classes of carbohydrate-active enzymes, glycoside hydrolases and glycosyltransferases, in the genome of Arabidopsis thaliana. The vast importance of these enzymes in cell-wall formation and degradation is revealed along with the unexpected dominance of pectin degradation in Arabidopsis, with at least 170 open-reading frames dedicated solely to this task.
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