The Streptococcus phage protein paratox is an intrinsically disordered protein.

IF 4.5 3区 生物学 Q1 BIOCHEMISTRY & MOLECULAR BIOLOGY
Protein Science Pub Date : 2024-06-01 DOI:10.1002/pro.5037
Iman Asakereh, Nicole R Rutbeek, Manvir Singh, David Davidson, Gerd Prehna, Mazdak Khajehpour
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引用次数: 0

Abstract

The bacteriophage protein paratox (Prx) blocks quorum sensing in its streptococcal host by directly binding the signal receptor and transcription factor ComR. This reduces the ability of Streptococcus to uptake environmental DNA and protects phage DNA from damage by recombination. Past work characterizing the Prx:ComR molecular interaction revealed that paratox adopts a well-ordered globular fold when bound to ComR. However, solution-state biophysical measurements suggested that Prx may be conformationally dynamic. To address this discrepancy, we investigated the stability and dynamic properties of Prx in solution using circular dichroism, nuclear magnetic resonance, and several fluorescence-based protein folding assays. Our work shows that under dilute buffer conditions Prx is intrinsically disordered. We also show that the addition of kosmotropic salts or protein stabilizing osmolytes induces Prx folding. However, the solute stabilized fold is different from the conformation Prx adopts when it is bound to ComR. Furthermore, we have characterized Prx folding thermodynamics and folding kinetics through steady-state fluorescence and stopped flow kinetic measurements. Our results show that Prx is a highly dynamic protein in dilute solution, folding and refolding within the 10 ms timescale. Overall, our results demonstrate that the streptococcal phage protein Prx is an intrinsically disordered protein in a two-state equilibrium with a solute-stabilized folded form. Furthermore, the solute-stabilized fold is likely the predominant form of Prx in a solute-crowded bacterial cell. Finally, our work suggests that Prx binds and inhibits ComR, and thus quorum sensing in Streptococcus, by a combination of conformational selection and induced-fit binding mechanisms.

链球菌噬菌体蛋白 paratox 是一种内在无序蛋白。
噬菌体蛋白 paratox(Prx)通过直接结合信号受体和转录因子 ComR,阻断链球菌宿主的法定量感应。这降低了链球菌吸收环境 DNA 的能力,并保护噬菌体 DNA 免受重组破坏。过去对 Prx:ComR 分子相互作用进行的表征工作显示,当 paratox 与 ComR 结合时,会形成一个有序的球状折叠。然而,溶液态生物物理测量结果表明,Prx 可能是构象动态的。为了解决这一差异,我们使用圆二色性、核磁共振和几种基于荧光的蛋白质折叠测定方法研究了 Prx 在溶液中的稳定性和动态特性。我们的研究表明,在稀释缓冲液条件下,Prx 本质上是无序的。我们还发现,加入渗透盐或稳定蛋白质的渗透溶质会诱导 Prx 折叠。然而,溶质稳定的折叠与 Prx 与 ComR 结合时的构象不同。此外,我们还通过稳态荧光和停流动力学测量鉴定了 Prx 的折叠热力学和折叠动力学。我们的结果表明,Prx 在稀溶液中是一种高度动态的蛋白质,其折叠和再折叠的时间范围在 10 毫秒以内。总之,我们的研究结果表明,链球菌噬菌体蛋白 Prx 是一种内在无序蛋白,与溶质稳定的折叠形式处于两态平衡。此外,溶质稳定折叠可能是 Prx 在溶质拥挤的细菌细胞中的主要形式。最后,我们的研究表明,Prx 通过构象选择和诱导拟合结合机制结合并抑制 ComR,从而抑制链球菌的法定量感应。
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来源期刊
Protein Science
Protein Science 生物-生化与分子生物学
CiteScore
12.40
自引率
1.20%
发文量
246
审稿时长
1 months
期刊介绍: Protein Science, the flagship journal of The Protein Society, is a publication that focuses on advancing fundamental knowledge in the field of protein molecules. The journal welcomes original reports and review articles that contribute to our understanding of protein function, structure, folding, design, and evolution. Additionally, Protein Science encourages papers that explore the applications of protein science in various areas such as therapeutics, protein-based biomaterials, bionanotechnology, synthetic biology, and bioelectronics. The journal accepts manuscript submissions in any suitable format for review, with the requirement of converting the manuscript to journal-style format only upon acceptance for publication. Protein Science is indexed and abstracted in numerous databases, including the Agricultural & Environmental Science Database (ProQuest), Biological Science Database (ProQuest), CAS: Chemical Abstracts Service (ACS), Embase (Elsevier), Health & Medical Collection (ProQuest), Health Research Premium Collection (ProQuest), Materials Science & Engineering Database (ProQuest), MEDLINE/PubMed (NLM), Natural Science Collection (ProQuest), and SciTech Premium Collection (ProQuest).
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