整合宿主因子是一种pH响应性蛋白质，能在酸性生物膜样条件下从DNA弯曲转变为DNA桥接
The Integration Host Factor is a pH-responsive protein that switches from DNA bending to DNA bridging in acidic biofilm-like conditions
AI总结：
研究揭示整合宿主因子在酸性条件下由DNA弯曲转为DNA桥接，通过pH调节其与DNA的相互作用，支撑生物膜结构。
摘要：
整合宿主因子（IHF）是一种与核蛋白结合的关键蛋白，对DNA压缩和生物膜稳定性至关重要。尽管其在细胞内DNA包装中的作用已被充分理解，但其在支架生物膜中的结构作用更加神秘，难以用其已知的DNA弯曲活性来解释。在此，我们研究了IHF-DNA相互作用如何在模拟细菌生物膜酸性微环境的pH范围内发生变化。通过进行全原子计算，我们发现低pH值会导致IHF残基的质子化发生变化，从而暴露带正电的区域。我们推测这些带正电的残基可能导致分子间DNA桥接，并通过单分子和批量实验测试了这一假设。我们发现，在生理pH下，IHF主要弯曲DNA，而在pH<5时，有明显证据显示IHF介导的分子间交联。我们的结果表明，pH显著调节IHF-DNA相互作用，并解释了IHF通过分子间交联支持生物膜机械结构的作用。
英文摘要：
The Integration Host Factor (IHF) is a nucleoid-associated protein critical for both DNA compaction and biofilm stability. While its role in DNA packaging within the cell is well understood, its structural role in scaffolding biofilms is more puzzling and difficult to reconcile with its known DNA bending activity. Here, we investigated how IHF-DNA interactions are modulated across a pH spectrum mimicking the acidic microenvironments of bacterial biofilms. By performing all-atom calculations we discovered that low pHs lead to a change in protonation of IHF residues, which in turn exposes positively charged patches. We then conjectured that these positively charged residues could lead to intermolecular DNA bridging and tested this hypothesis through single-molecule and bulk assays. We discovered that while at physiological pH IHF mostly bends DNA, at pH < 5 there is clear evidence of IHF-mediated intermolecular crosslinking. Our results demonstrate that pH significantly modulates IHF-DNA interactions and explains the structural role played by IHF in supporting biofilm mechanics through intermolecular crosslinking.
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