Characterization of a tomato protein that inhibits a xyloglucan-specific endoglucanase.

摘要: A basic, 51 kDa protein was purified from suspension-cultured tomato and shown to inhibit the hydrolytic activity of a xyloglucan-specific endoglucanase (XEG) fungus Aspergillus aculeatus. The (Lycopersicon esculentum) protein, termed XEG inhibitor (XEGIP), inhibits by forming 1 : protein:protein complex with Ki approximately 0.5 nm. To our knowledge, XEGIP is first reported proteinaceous any endo-beta-1,4-glucanase, including cellulases. cDNA encoding cloned sequenced. Database analysis revealed homology carrot extracellular dermal glycoprotein (EDGP), which has putative role in plant defense. also sequence similarity ESTs broad range species, suggesting that XEGIP-like genes are widely distributed kingdom. Although Southern detected only single gene tomato, at least five other sequences have been identified. Similar small families present plants, Arabidopsis. some two previously characterized proteins, basic globulin 7S soybean conglutin gamma lupin. Several amino acids sequence, notably 8 12 cysteines, generally conserved all proteins we encountered, fundamental structural similarity. Northern expressed vegetative tissues expanding maturing fruit, but downregulated during ripening.