Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 2010 Feb 2;107(5):2230-4. doi: 10.1073/pnas.0910560107. Epub 2010 Jan 13.
Bacillus subtilis forms biofilms whose constituent cells are held together by an extracellular matrix. Previous studies have shown that the protein TasA and an exopolysaccharide are the main components of the matrix. Given the importance of TasA in biofilm formation, we characterized the physicochemical properties of this protein. We report that purified TasA forms fibers of variable length and 10-15 nm in width. Biochemical analyses, in combination with the use of specific dyes and microscopic analyses, indicate that TasA forms amyloid fibers. Consistent with this hypothesis, TasA fibers required harsh treatments (e.g., formic acid) to be depolymerized. When added to a culture of a tasA mutant, purified TasA restored wild-type biofilm morphology, indicating that the purified protein retained biological activity. We propose that TasA forms amyloid fibers that bind cells together in the biofilm.
枯草芽孢杆菌形成生物膜，其组成细胞由细胞外基质结合在一起。先前的研究表明，TasA 蛋白和一种胞外多糖是基质的主要成分。鉴于 TasA 在生物膜形成中的重要性，我们对该蛋白的物理化学性质进行了表征。我们报告说，纯化的 TasA 形成长度可变且宽度为 10-15nm 的纤维。生化分析结合使用特定的染料和显微镜分析表明，TasA 形成淀粉样纤维。与该假设一致，TasA 纤维需要苛刻的处理（例如甲酸）才能解聚。当添加到 tasA 突变体的培养物中时，纯化的 TasA 恢复了野生型生物膜形态，表明纯化的蛋白保留了生物活性。我们提出 TasA 形成淀粉样纤维，将生物膜中的细胞结合在一起。
