如何微小的序列变化使MFS传送器的机械多样性? 在NarU中出现的Symport的一个原子层次的理由
Tanner J Dean1, Jiangyan Feng2, Diwakar Shukla2,1,3,4,5
1Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
bioRxiv : the preprint server for biology
|December 3, 2025
概括
像NarU这样的细菌膜载体的微小序列变化可以显著改变它们的传输机制,从抗载体转换为潜在的同载体活动. 这凸显了微妙的残留物差异如何重编程传送器功能.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 分子生物物理学 分子生物物理学
背景情况:
- 密切相关的膜载体可以表现出不同的运输机制,尽管序列变化最小.
- 酸盐和酸盐的运输在细菌中,对于无氧呼吸至关重要,涉及主要促进者超级家族 (MFS) 运输器,如NarK和NarU.
- 纳克作为酸盐/酸盐反载体起作用,而纳鲁的运输机制尚未完全理解,有证据表明它是同载体.
研究的目的:
- 为了阐明细菌MFS载体NarU的运输机制.
- 将NarU的结构动力学和运输原理与已知反载体NarK的结构动力学和运输原理进行比较.
- 在密切相关的运输商中确定负责改变运输机制的结构决定因素.
主要方法:
- 适应性分子动力学模拟被用来探索NarU的结构格局.
- 马尔科夫状态建模被用来分析NarU的自由能量景观.
- 使用计算方法将NarU的行为与NarK的既定机制进行对比.
主要成果:
- NarU 呈现出与 NarK 不同的构造性自由能量景观,有利于面向外的状态.
- 在NarU中发现了一种稳定的apo-occluded中间体,无法进入antiporters,被确定为NarU.
- 关键的结构变化,包括氨酸关对旋转和甘氨酸替代,与NarU改变的关能量和共同运输的潜力有关.
结论:
- 微妙的序列变化,特别是结合口袋和转位途径中的战略残留物替代,可以从根本上重新编程传送器功能.
- 这些发现表明,微小的结构适应如何可以切换传送器的机制,例如从反传送器到同传送器活动.
- 该研究提供了MFS传送器的可塑性和分离的运输机制的分子基础的见解.
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