一个Clostridioides difficile内素调节毒素分泌而没有细胞溶解
Milena M Awad1, Chathura D Suraweera1, Callum J Vidor1
1Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, 3800, Australia.
Communications biology
|August 23, 2024
概括
困难菌通过一种新的机制分泌毒素. 一种特定的糖胺酶,M7404_02200,促进了大型密闭性葡萄糖化毒素 (LCGT) 的非性释放.
科学领域:
- 微生物学 微生物学
- 细菌病原体的产生
- 分子生物学分子生物学
背景情况:
- 闭膜体,包括Clostridioides difficile,产生重大闭膜体葡萄糖化毒素 (LCGTs),对疾病至关重要.
- 这些毒素的分泌机制在很大程度上仍未被描述.
- 最近发现一种类似霍林的蛋白质对于毒素的释放至关重要.
研究的目的:
- 调查假定氨酸在Clostridioides difficile的TcdA和TcdB分泌中的作用.
- 为了确定Clostridia是否使用基于lysin的毒素释放系统,类似于细菌菌体.
主要方法:
- 两个保存的假定 lysins (M7404_01910和M7404_02200) 的序列分析和结构建模.
- 基因破坏实验,以评估每个假定lysin对毒素分泌的贡献.
- 使用重组M7404_02200的丁糖溶解试验.
主要成果:
- 预测M7404_01910和M7404_02200都是N-乙烯基muramoyl-l-alanine胺基酶.
- 只有M7404_02200被发现对TcdA和TcdB的分泌至关重要.
- 由M7404_02200介导的毒素分泌以非式的方式发生.
- 再组合M7404_02200显示活跃的糖胺酶活性.
结论:
- 在Clostridioides difficile.中,M7404_02200作为糖胺酶的功能.
- 这种氨基酶在LCGTs,特别是TcdA和TcdB的非性分泌中发挥着关键作用.
- 这些发现揭示了C. difficile中一种新的毒素分泌机制,与典型的菌体溶解不同.
相关概念视频
01:23Stringent Response in E. coli
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...
01:12Bacterial Toxins
Bacterial toxins are sophisticated virulence factors that enable pathogenic bacteria to interact with, invade, and damage host tissues. These toxins fall broadly into two types: protein exotoxins, which are secreted into the environment and target specific host receptors, and lipopolysaccharide endotoxins, which are structural components of the bacterial outer membrane released primarily during bacterial lysis or membrane shedding. Exotoxins generally act more selectively, binding to cell...
01:29Tetanus
Tetanus is a life-threatening neurological disorder characterized by persistent muscle contractions and spastic paralysis. It is caused by Clostridium tetani, a motile, Gram-positive, rod-shaped, obligate anaerobe. These bacteria produce terminal endospores, giving them a distinctive “lollipop” or “tennis-racket” appearance. They thrive in anaerobic environments, such as those found in deep puncture wounds.Once introduced into the body, the spores germinate into vegetative cells. These cells...
01:22Botulism
Botulism is a life-threatening neuroparalytic condition caused by botulinum neurotoxin, which is produced by the bacterium Clostridium botulinum, a Gram-positive, spore-forming, obligate anaerobe.In adults, the toxin enters the body in different ways: in foodborne botulism, the preformed toxin is absorbed in the intestine. In wound botulism, spores grow in injured tissue and release the toxin into the blood. Infant botulism differs mechanistically from adult forms. In infants, botulism commonly...
01:28Diphtheria
Diphtheria is an acute, toxin-mediated infectious disease that primarily affects the upper respiratory tract. It is caused by Corynebacterium diphtheriae, a Gram-positive, pleomorphic rod that lacks spore-forming capability and exhibits a characteristic club-shaped morphology under microscopic examination. While C. diphtheriae can asymptomatically colonize mucosal surfaces, clinical disease manifests only when the bacterial strain is lysogenized by a specific β-corynephage. This phage...