Romero Diego, Kolter Roberto
Institute of Subtropical and Mediterranean Hortofruticulture "La Mayora"- CSIC, and Department of Microbiology, University of Malaga, Malaga, Spain.
Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, USA.
Int Microbiol. 2014 Jun;17(2):65-73. doi: 10.2436/20.1501.01.208.
The term amyloidosis is used to refer to a family of pathologies altering the homeostasis of human organs. Despite having a name that alludes to starch content, the amyloid accumulations are made up of proteins that polymerize as long and rigid fibers. Amyloid proteins vary widely with respect to their amino acid sequences but they share similarities in their quaternary structure; the amyloid fibers are enriched in β-sheets arranged perpendicular to the axis of the fiber. This structural feature provides great robustness, remarkable stability, and insolubility. In addition, amyloid proteins specifically stain with certain dyes such as Congo red and thioflavin-T. The aggregation into amyloid fibers, however, it is not restricted to pathogenic processes, rather it seems to be widely distributed among proteins and polypeptides. Amyloid fibers are present in insects, fungi and bacteria, and they are important in maintaining the homeostasis of the organism. Such findings have motivated the use of the term "functional amyloid" to differentiate these amyloid proteins from their toxic siblings. This review focuses on systems that have evolved in bacteria that control the expression and assembly of amyloid proteins on cell surfaces, such that the robustness of amyloid proteins are used towards a beneficial end.
淀粉样变性这个术语用于指代一系列改变人体器官稳态的病理学情况。尽管其名称暗示与淀粉含量有关，但淀粉样沉积物是由聚合成细长且坚硬纤维的蛋白质组成。淀粉样蛋白在氨基酸序列方面差异很大，但它们在四级结构上有相似之处；淀粉样纤维富含垂直于纤维轴排列的β折叠。这种结构特征赋予了其很强的坚固性、显著的稳定性和不溶性。此外，淀粉样蛋白能用某些染料如刚果红和硫黄素 - T进行特异性染色。然而，聚集成淀粉样纤维并不局限于致病过程，相反，它似乎在蛋白质和多肽中广泛存在。淀粉样纤维存在于昆虫、真菌和细菌中，并且在维持生物体的稳态中很重要。这些发现促使人们使用“功能性淀粉样蛋白”这一术语来区分这些淀粉样蛋白与其有毒的同类。本综述聚焦于细菌中进化出的系统，这些系统控制淀粉样蛋白在细胞表面的表达和组装，从而使淀粉样蛋白的坚固性被用于有益的目的。
