クロストリジウムディフィシル毒素BによるRhoタンパク質のグルコシル化
1Institut für Pharmakologie und Toxikologie, Universität des Saarlandes, Homburg/Saar, Germany.
Nature
|June 8, 1995
まとめ
クロストリジウムディフィシル毒素Bは,グルコースを加えることでRhoAGTPアゼを改変し,それを無効化する. このグルコシル化RhoAはアクチン細胞骨格を破壊し,細胞損傷を引き起こし,大腸炎に寄与します.
科学分野:
- 微生物学 微生物学とは
- 細胞生物学 細胞生物学
- バイオケミストリー バイオケミストリー
背景:
- クラストリジウムディフィシル毒素AとBは,抗生物質に関連した大腸炎を引き起こす.
- これらの毒素は,マイクロフィラメントの細胞骨格を分解することによって細胞毒性を誘発します.
- 毒素Bは,アクチン細胞骨格の調節に不可欠なRhoA GTPaseを標的とする.
研究 の 目的:
- クロストリジウムディフィシル毒素BがRhoA.に影響を与える特定のメカニズムを調査する.
- 改変とそのRhoA機能への影響を特定するために.
主な方法:
- タンデム電気スプレー質量スペクトロメトリを使用して,改変を特定し,局所化しました.
- UDP-グルコースは,コスブストラートとしてin vitroで使用されました.
- 修飾されたRhoAを培養細胞に微量注入する.
主要な成果:
- 毒素Bは,Threonine 37でRhoAのモノグルコシライゼーションを触媒化する.
- UDP-グルコースは,このモノグルコシライゼーションの選択的副基材として機能します.
- 微量注射されたグルコシル化RhoAはアクチン線維の分解を引き起こし,支配的-負の活性を示した.
結論:
- クロストリジウムディフィシル毒素Bは,モノグルコシライゼーションによってRhoAを無活性化します.
- この改変はアクチン細胞骨格を破壊し,毒素の細胞毒性効果に貢献します.
- このグルコシライゼーションメカニズムをターゲットにすることで,C. difficile感染症に対する治療戦略を提供することができます.
さらに関連する動画
関連する概念動画
Oligosaccharide Assembly
Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...
Multiple sugar molecules that may or may...
Protein Folding Quality Check in the RER
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...
Small GTPases - Ras and Rho
Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
Three regulatory proteins control their activity:
GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...
Bacterial 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...
Diphtheria
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...


