作为细胞外信号的Mg2+:沙门氏菌毒性的环境调节
E García Véscovi1, F C Soncini, E A Groisman
1Washington University School of Medicine, Department of Molecular Microbiology, St. Louis, Missouri 63110, USA.
Cell
|January 12, 1996
概括
离子 (Mg2+) 在沙门氏菌型菌中起到关键信号的作用,调节PhoP/PhoQ毒性系统. 这一发现重新定义了离子在细胞信号传递和细菌毒性中的作用.
科学领域:
- 微生物学 微生物学
- 分子生物学分子生物学
- 细菌病原体的产生
背景情况:
- 传统上,离子在细胞信号转导中并不被认为是主要的信号分子.
- 沙门氏杆菌的PhoP/PhoQ系统是已知的毒性调节器.
- 之前的研究没有确定Mg2+作为PhoP/PhoQ系统的直接调节器.
研究的目的:
- 调查离子 (Mg2+) 是否作为调节PhoP/PhoQ毒性调节系统的信号.
- 确定Mg2+影响PhoP/PhoQ调节的基因表达的机制.
主要方法:
- 在不同的Mg2+度下评估了6个PhoP激活基因的基因表达模式.
- 评估了野生型沙门氏菌的表型变化,这种沙门氏菌在双价离子的生理度中生长.
- 使用Mg2+分析了PhoQ蛋白在周等离子域的构造变化.
- 在PhoQ的Mg2+感应领域引入了突变,以评估它们的影响.
主要成果:
- 物理度的Mg2+抑制了PhoP激活基因的转录.
- 野生型沙门氏菌在Mg2+的存在下生长时表现出PhoP阴性表型.
- 表明Mg2+改变了PhoQ周等离子域的构造,证实它是Mg2+传感器.
- 在PhoQ的感知领域发生的突变改变了它的Mg2+敏感性,并导致沙门氏菌发病.
结论:
- 离子 (Mg2+) 作为直接信号,调节沙门氏菌中的PhoP/PhoQ毒性调节系统.
- 该PhoQ蛋白作为Mg2+的传感器,将环境Mg2+水平纳入调节级联.
- 这一发现扩大了对信号传导和细菌毒性机制中的离子作用的理解.
相关概念视频
01:30Bacterial Signaling
29.8K
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
29.8K
01:28Global Regulatory Systems
959
Global regulatory systems in bacteria enable rapid and coordinated responses to environmental changes by integrating sensory inputs with gene expression, ensuring efficient adaptation to fluctuating conditions. Key global regulatory mechanisms include regulons, two-component systems, sigma factors, and secondary messengers.Regulons and Global RegulatorsA regulon is a collection of genes and operons controlled by a common global regulator. These regulators enable bacteria to prioritize resource...
959
01:28Gene Regulation in Microbial Communities: Quorum Sensing
954
Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
954
01:23Stringent Response in E. coli
528
Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
528
01:16Transduction
3.0K
Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome...
3.0K
01:28Regulation of Bacterial Virulence
76
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
76