Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109-1048.
Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
Proc Natl Acad Sci U S A. 2017 Nov 14;114(46):12184-12189. doi: 10.1073/pnas.1708805114. Epub 2017 Oct 30.
During biofilm formation, and other Enterobacteriaceae produce an extracellular matrix consisting of curli amyloid fibers and cellulose. The precursor of curli fibers is the amyloidogenic protein CsgA. The human systemic amyloid precursor protein transthyretin (TTR) is known to inhibit amyloid-β (Aβ) aggregation in vitro and suppress the Alzheimer's-like phenotypes in a transgenic mouse model of Aβ deposition. We hypothesized that TTR might have broad antiamyloid activity because the biophysical properties of amyloids are largely conserved across species and kingdoms. Here, we report that both human WT tetrameric TTR (WT-TTR) and its engineered nontetramer-forming monomer (M-TTR, F87M/L110M) inhibit CsgA amyloid formation in vitro, with M-TTR being the more efficient inhibitor. Preincubation of WT-TTR with small molecules that occupy the T4 binding site eliminated the inhibitory capacity of the tetramer; however, they did not significantly compromise the ability of M-TTR to inhibit CsgA amyloidogenesis. TTR also inhibited amyloid-dependent biofilm formation in two different bacterial species with no apparent bactericidal or bacteriostatic effects. These discoveries suggest that TTR is an effective antibiofilm agent that could potentiate antibiotic efficacy in infections associated with significant biofilm formation.
在生物膜形成过程中，肠杆菌科和其他细菌会产生一种由卷曲菌纤维和纤维素组成的细胞外基质。卷曲菌纤维的前体是淀粉样蛋白 CsgA。人类系统性淀粉样前体蛋白转甲状腺素（TTR）已知在体外抑制淀粉样-β（Aβ）聚集，并在 Aβ沉积的转基因小鼠模型中抑制类似阿尔茨海默病的表型。我们假设 TTR 可能具有广泛的抗淀粉样活性，因为淀粉样蛋白的生物物理特性在很大程度上是跨物种和生物界保守的。在这里，我们报告说，人类 WT 四聚体 TTR（WT-TTR）及其工程化的非四聚体形成单体（M-TTR，F87M/L110M）均可在体外抑制 CsgA 淀粉样形成，其中 M-TTR 的抑制效率更高。用占据 T4 结合位点的小分子预先孵育 WT-TTR 会消除四聚体的抑制能力；然而，它们并没有显著降低 M-TTR 抑制 CsgA 淀粉样形成的能力。TTR 还抑制了两种不同细菌物种中依赖于淀粉样蛋白的生物膜形成，而没有明显的杀菌或抑菌作用。这些发现表明，TTR 是一种有效的抗生物膜剂，可增强与严重生物膜形成相关的感染中抗生素的疗效。
