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ADP-ribosylation of myelin basic protein by cholera toxin
Abstract:
Cholera toxin ADP-ribosylates four types of myelin basic proteins (MBPs) of Mr 14,000, 17,500, 19,000 and 22,000 in rat brain myelin. On an analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, MBP underwent mono- and multi-(ADP-ribosyl)ation by cholera toxin and thus modified MBP migrated on the gel as several discrete protein bands, the molecular masses of which were apparently larger by 500-2000 daltons than that of the corresponding untreated MBP. On average, 1.1 mol of ADP-ribosyl residue was incorporated into 1 mol of MBP. Four types of purified MBPs were also ADP-ribosylated by cholera toxin dependent on GTP and the protein factor for the ADP-ribosylation. The results show evidence that MBP is one of major and specific substrates of cholera toxin in brain membranes.
Insights
Cholera toxin modifies myelin basic proteins (MBPs) in rat brain membranes. This research identifies MBPs as key targets for cholera toxin in the brain.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Myelin basic proteins (MBPs) are crucial components of the myelin sheath in the central nervous system.
- Cholera toxin is a potent bacterial toxin known to ADP-ribosylate various cellular proteins.
Purpose of the Study:
- To investigate the interaction between cholera toxin and myelin basic proteins (MBPs) in rat brain.
- To determine if MBPs are substrates for cholera toxin-mediated ADP-ribosylation.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze protein modification.
- ADP-ribosylation assays were performed on purified MBPs in the presence of GTP and a protein factor.
Main Results:
- Cholera toxin ADP-ribosylated four distinct molecular weight forms of MBP (14,000, 17,500, 19,000, and 22,000 Da).
- ADP-ribosylated MBP showed increased molecular mass on SDS-PAGE, indicating mono- and multi-ADP-ribosylation.
- An average of 1.1 mol of ADP-ribosyl residue was incorporated per mole of MBP.
- Purified MBPs were confirmed as substrates for cholera toxin-dependent ADP-ribosylation.
Conclusions:
- Myelin basic proteins (MBPs) are identified as major and specific substrates of cholera toxin in brain membranes.
- This finding suggests a potential role for cholera toxin in modifying myelin structure or function within the brain.