科研之友
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摘要
Germins and germin-like proteins constitute a large and very diverse family of ubiquitous plant proteins. They belong to the cupin superfamily of proteins which name comes from the domain of beta-barrel structure (from the Latin Cupa - small barrel). It is evolutionary conserved domain localized in C- terminal end. It consists of two amino acid sequence motifs: 1 and 2, described as the 'germin box'. Cupin domain determines the high thermal stability, which is come out of the presence of disulphide bridges and the glycosylation degree. The presence of domain cupin suitable these proteins resistance to the protease protein. Germins occur in two isoforms gf-2.8 and gf-3.8 encoded by the gf-2.8 and gf-3.8 genes, active during the embryos germination of all economically important crops. In both genes there are regions without introns, which encode 224 amino acids, showing 90% homology. It is interesting that in the 5' region of gf-2.8 gene; there are two sequence motifs characteristic of auxin genes. There has been distinguished six subfamilies of germin-like proteins with different enzymatic activity. There has been recognized a lot of germin-like proteins involved in plant defense responses against pathogens and pests. Defensive activity of GLP was found in apoplast which are expressed and react with the cell wall by facilitating an early response to pathogen attack. Particularly important are GLPs with oxalate oxidase activity, because they lower levels of oxalate, which is a virulence factor produced by several fungal pathogens. Transcription of the genes encoding germins and oxalate oxidase activity is stimulated by fungal infections and some metal ions. Wheat germin also have enormous potential for commercial applications because of the previously mentioned unusual resistance to proteases, high stability and resistance to heat.
- 出版日期2012
