title: Proteinaceous inhibitors of microbial xylanases.
abstract: At the end of 1990s two structurally different proteinaceous inhibitors of xylanases were discovered in the grain of wheat (Triticum aestivum). They were named TAXI (T. aestivum xylanase inhibitor) and XIP (xylanase-inhibiting protein). Later it was shown that TAXI and XIP in wheat are present in several isoforms encoded by different genes. TAXI- and XIP-like inhibitors have also been found in other cereals-barley, rye, rice, maize, etc. All these proteins can specifically inhibit activity of fungal and bacterial xylanases belonging to families 10 and 11 of glycoside hydrolases, but they do not affect endogenous enzymes produced by plants. A common viewpoint is that the presence of proteinaceous inhibitors in cereals is a response of plants to pathogenic attack by microorganisms. A few years ago, an inhibitor of a third type was discovered in wheat. It was named TLXI (thaumatin-like xylanase inhibitor) because of its similarity to the thaumatin family of plant proteins. In this review, the occurrence of proteinaceous inhibitors of xylanases in different cereals, their specificity towards fungal and bacterial enzymes, as well as structural features responsible for enzyme sensitivity to various types of inhibitors are discussed.
authors.affiliation: Lomonosov Moscow State University, Russia. avgusakov@enzyme.chem.msu.ru
authors.forename: A V
authors.initials: AV
authors.lastname: Gusakov
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005658:Fungi / Q000201:enzymology*; D047908:Intracellular Signaling Peptides and Proteins; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014908:Triticum / Q000235:genetics / Q000378:metabolism*; D014995:Xylosidases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010940:Plant Proteins; C422246:TAXI I protein, Triticum aestivum; C485063:XIP-I protein, Triticum aestivum; D014995:Xylosidases