Biofilms, microbial communities enclosed in the self-produced extracellular matrix, have a significant impact on human health, environment, and industry. The pathogen is recognized as one of the most frequent causes of biofilm-related infections. Phenol-soluble modulins (PSMs) serve as a crucial component, fortifying biofilm matrix through self-assembly into amyloid fibrils, which enhances colonization and resistance to antibiotics. However, the role of shear rate, one of the critical physiological factors within blood vessels, on the formation of PSM amyloids remains poorly understood. In this work, using a combination of thioflavin T fluorescence kinetic studies, circular dichroism spectrometry, and electron microscopy, we demonstrated that shear rates ranging from 150 to 300 s accelerate fibrillation of PSMα1, α3, and α4 into amyloids, resulting in elongated amyloid structures. Furthermore, PSMα1, α3, and α4 predominantly self-assembled into amyloid fibers with a cross-α structure under shear conditions, deviating from the typical β-sheet configuration of PSM amyloids. These findings imply the role of shear rates within the bloodstream on enhancing PSM self-assembly that is associated with biofilm formation.

中文翻译：

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剪切速率对生物膜肽酚溶性调节蛋白淀粉样蛋白形成的作用

生物膜，即封闭在自身产生的细胞外基质中的微生物群落，对人类健康、环境和工业具有重大影响。该病原体被认为是生物膜相关感染的最常见原因之一。酚溶性调节蛋白 (PSM) 是一种重要成分，通过自组装成淀粉样原纤维来强化生物膜基质，从而增强定植和对抗生素的耐药性。然而，剪切率（血管内关键的生理因素之一）对 PSM 淀粉样蛋白形成的作用仍知之甚少。在这项工作中，结合硫黄素 T 荧光动力学研究、圆二色光谱法和电子显微镜，我们证明 150 至 300 秒的剪切速率会加速 PSMα1、α3 和 α4 纤维化成淀粉样蛋白，从而导致淀粉样蛋白结构伸长。此外，PSMα1、α3和α4在剪切条件下主要自组装成具有交叉α结构的淀粉样蛋白纤维，这偏离了PSM淀粉样蛋白典型的β-折叠结构。这些发现意味着血流中的剪切速率对增强与生物膜形成相关的 PSM 自组装的作用。