在富含酸盐的环境中,酸盐歧视的分子基础
Mikael Elias1, Alon Wellner, Korina Goldin-Azulay
1Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel. mikael.elias@weizmann.ac.il
Nature
|October 5, 2012
概括
细胞必须区分有毒酸盐和必需酸盐. 研究人员发现,细菌酸盐结合蛋白 (PBPs) 可以区分这些相似的离子,防止代谢中断.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 微生物学 微生物学
背景情况:
- 酸盐和酸盐具有相似的化学特性,对生物系统构成挑战.
- 酸盐对生命至关重要,而酸盐是有毒的,需要区分机制.
- 细胞吸收系统,如周等离子体酸盐结合蛋白 (PBPs),必须区分这些离子.
研究的目的:
- 阐明细菌酸盐运输系统区分酸盐和酸盐的分子机制.
- 研究PBPs中选择性酸盐结合的结构基础,特别是在富含酸盐的环境中.
主要方法:
- 检查了来自细菌ABC型运输系统的周等离子体酸盐结合蛋白 (PBPs),包括来自Halomonas菌株GFAJ-1的蛋白质.
- 确定了Pseudomonas fluorescens PBP与酸盐和酸盐结合的亚斯特罗姆分辨率晶体结构.
- 分析了绑定模式和动力参数,以量化歧视比.
主要成果:
- 所有测试的PBPs都显示出显著的差异,酸盐与酸盐的结合至少是500倍.
- 来自Halomonas GFAJ-1的一个特定的PBP表现出约4,500倍的歧视,并且在酸盐限制下高度表达.
- 结构分析揭示了一种独特的结合模式,涉及二极和排斥相互作用,利用酸盐和酸盐之间的微小尺寸差异.
结论:
- 细菌PBP具有分子机制,可以有效地歧视有毒酸盐,确保选择性吸收必需酸盐.
- 鉴定的结构特征解释了酸盐运输系统的高选择性,即使在酸盐度高的环境中也是如此.
- 这种区分对于维持细胞代谢和预防细菌中毒性至关重要.
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