Pelegrini Patrícia B, Franco Octávio L
Centro de Análises Proteômicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, SGAN Quadra 916, Módulo B, Av. W5 Norte 70.790-160 Asa Norte Brasília/DF, Brazil.
Int J Biochem Cell Biol. 2005 Nov;37(11):2239-53. doi: 10.1016/j.biocel.2005.06.011.
This review focuses on the first plant defense protein class described in literature, with growth inhibition activity toward pathogens. These peptides were named gamma-thionins or defensins, which are small proteins that can be classified into four main subtypes according to their specific functions. Gamma-thionins are small cationic peptides with different and special abilities. They are able to inhibit digestive enzymes or act against bacteria and/or fungi. Current research in this area focuses particularly these two last targets, being the natural crop plant defenses improved through the use of transgenic technology. Here, we will compare primary and tertiary structures of gamma-thionins and also will analyze their similarities to scorpion toxins and insect defensins. This last comparison offers some hypothesis for gamma-thionins mechanisms of action against certain pathogens. This specific area has benefited from the recent determination of many gamma-thionin structures. Furthermore, we also summarize molecular interactions between plant gamma-thionins and fungi receptors, which include membrane proteins and lipids, shedding some light over pathogen resistance. Researches on gamma-thionins targets could help on plant genetic improvement for production of increased resistance toward pathogens. Thus, positive results recently obtained for transgenic plants and future prospects in the area are also approached. Finally, gamma-thionins activity has also been studied for future drug development, capable of inhibit tumor cell growth in human beings.
本综述聚焦于文献中描述的第一类植物防御蛋白，其对病原体具有生长抑制活性。这些肽被命名为γ-硫堇或防御素，它们是小蛋白，可根据其特定功能分为四种主要亚型。γ-硫堇是具有不同特殊能力的小阳离子肽。它们能够抑制消化酶或对抗细菌和/或真菌。该领域目前的研究尤其关注这两个最后的靶点，即通过转基因技术改善天然作物的植物防御。在此，我们将比较γ-硫堇的一级和三级结构，还将分析它们与蝎毒素和昆虫防御素的相似性。最后这种比较为γ-硫堇针对某些病原体的作用机制提供了一些假设。这一特定领域受益于最近许多γ-硫堇结构的确定。此外，我们还总结了植物γ-硫堇与真菌受体之间的分子相互作用，其中包括膜蛋白和脂质，这为病原体抗性提供了一些线索。对γ-硫堇靶点的研究有助于植物遗传改良，以提高对病原体的抗性。因此，本文还探讨了转基因植物最近取得的积极成果以及该领域的未来前景。最后，γ-硫堇的活性也已针对未来药物开发进行了研究，其能够抑制人类肿瘤细胞的生长。
