Related Experiment Video
Updated: Aug 16, 2025
10:30
A High-throughput-compatible FRET-based Platform for Identification and Characterization of Botulinum Neurotoxin Light Chain Modulators
Published on: December 27, 2013
5.4K
How Botulinum Neurotoxin Light Chain A1 Maintains Stable Association with the Intracellular Neuronal Plasma Membrane
Alexander P Gardner1, Joseph T Barbieri1, Sabine Pellett2
1Microbiology and Immunology, Medical College, Wisconsin 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Toxins
|December 22, 2022
Summary
Botulinum neurotoxin serotype A (BoNT/A) potency is linked to its light chain (LC/A) binding to SNAP-25. A specific 59-amino acid region (MLD) directs LC/A3 to the plasma membrane, revealing key structural elements for BoNT/A potency.
Area of Science:
- Molecular Biology
- Neuroscience
- Biochemistry
Background:
- Botulinum neurotoxin serotype A (BoNT/A), a potent neurotoxin used therapeutically, consists of a catalytic Light Chain (LC/A) and a Heavy Chain (HC/A).
- Previous research indicated BoNT/A potency correlates with stable plasma membrane localization, with a low homology domain (amino acids 268-357) identified as crucial for LC/A1 co-localization with SNAP-25.
- LC/A3, however, was observed in the cytosol, suggesting differences in localization mechanisms among BoNT/A subtypes.
Purpose of the Study:
- To identify the specific structural elements within the LC/A low homology domain responsible for directing the light chain to the plasma membrane.
- To elucidate the molecular mechanisms underlying the stable co-localization of LC/A with SNAP-25, contributing to BoNT/A potency.
Main Methods:
- Utilized steady-state and live-cell imaging techniques to observe the behavior of engineered cytosolic LC/A3 derivatives (LC/A3V) in Neuro-2A cells.
- Introduced structural elements from the LC/A1 low homology domain into LC/A3V to assess their impact on plasma membrane localization.
- Employed informatics and experimental validation to analyze the contribution of predicted regions (R1 and R2) within the identified MLD (residues 275-334).
Main Results:
- A 59-amino acid region (residues 275-334), termed the MLD, was sufficient to redirect the cytosolic LC/A3V to the plasma membrane, achieving co-localization with SNAP-25.
- Both the R1 region (residues 275-300) and the R2 region (residues 302-334) within the MLD were found to contribute independently to the stable co-localization of LC/A1 with SNAP-25.
- These findings highlight specific structural determinants within the light chain that govern its interaction with the plasma membrane and SNAP-25.
Conclusions:
- The MLD (residues 275-334) contains critical structural elements (R1 and R2) essential for the plasma membrane association of LC/A1 with SNAP-25.
- Understanding these structural contributions provides insight into the molecular basis for the light chain's role in the high potency of BoNT/A1.
- This research may pave the way for developing targeted BoNT/A therapies with enhanced efficacy and specificity.
Related Concept Videos
01:26Directly Acting Muscle Relaxants: Dantrolene and Botulinum Toxin
723
Directly acting muscle relaxants like dantrolene and botulinum toxin (BoNT) have distinct mechanisms and applications. Dantrolene, a hydantoin derivative, acts on the ryanodine receptor (RYR1) in skeletal muscle cells. RYR1 are calcium channels present at the sarcoplasmic reticulum membrane. In response to excitation, they release calcium ions from the sarcoplasmic reticulum to the cytosol. Calcium promotes actin-myosin-mediated contraction of muscles.
The binding of dantrolene to the RYR1...
The binding of dantrolene to the RYR1...
723
01:26Chemical Synapses
9.0K
Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
9.0K
01:26Fusion of Secretory Vesicles with the Plasma Membrane
11.2K
Proteins and neurotransmitters in secretory vesicles can be released from a cell upon vesicle docking, priming, and fusion with the plasma membrane. Vesicles are docked and primed in preparation for the quick exocytosis of their contents in response to a stimulus. The fusion process is mainly carried out by a SNAP Receptor or SNARE complex, consisting of synaptobrevin, syntaxin-1, and SNAP-25.
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
In 1993, Jim Rothman proposed that the antiparallel pairing of vesicular and transmembrane SNAREs, or...
11.2K
01:29Neuromuscular Junction And Blockade
3.3K
The site of chemical communication between a motor neuron and a muscle fiber is called the neuromuscular junction (NMJ). The end of the motor neuron at the NMJ divides into a cluster of synaptic end bulbs. The cytoplasm of these bulbs consists of synaptic vesicles enclosing acetylcholine molecules, the principal neurotransmitter released at the NMJ. The region opposite the synaptic bulb that ends in the muscle fiber is called the motor end plate, which has acetylcholine receptors. Within the...
3.3K
01:23Cholinergic Neurons: Neurotransmission
3.2K
Cholinergic neurotransmission involves the synthesis and the release of acetylcholine (ACh) in order to transmit nerve impulses across the synapse. The process begins with the synthesis of acetyl CoA, a precursor for ACh, from ATP, acetate, and coenzyme A in the mitochondria. Choline, another vital precursor, is transported inside the neuron through choline transporters, including high-affinity choline transporter CHT1, low-affinity choline transporter CTL1, and lower-affinity choline...
3.2K
01:20Myasthenia Gravis: Overview and Treatment
1.8K
Myasthenia gravis is a neuromuscular transmission disorder characterized by weakness and increased fatigability of skeletal muscles. It is an autoimmune disease affecting approximately one in 2000 people, where antibodies against the α1 subunit of nicotinic acetylcholine receptors are produced.
These antibodies interfere with the function of the nicotinic receptors in three ways: by binding to the receptor and disrupting acetylcholine binding; by causing cross-linking of receptors which...
These antibodies interfere with the function of the nicotinic receptors in three ways: by binding to the receptor and disrupting acetylcholine binding; by causing cross-linking of receptors which...
1.8K