Some types of bacteria have the ability to punch holes into other cells and kill them. They do this by releasing specialized proteins called "pore-forming toxins" (PFTs) that latch onto the cell's membrane and form a tube-like channel that goes through it. This hole (structure?) across the membrane is called a pore. Punctured by multiple PFTs, the target cell self-destructs.
However, PFTs have garnered much interest beyond bacterial infections. The nano-sized pores that they form are used for "sensing" biomolecules: a biological molecule e.g. DNA or RNA, passes through the nanopore like a string steered by a voltage, and its individual components (e.g. nucleic acids in DNA) give out distinct electrical signals that can be read out. In fact, nanopore sensing is already on the market as a major tool for DNA or RNA sequencing.
Publishing in Nature Communications, scientists have studied another major PFT that can be used effectively for more complex sensing, such as protein sequencing. The toxin is aerolysin, which is produced by the bacterium Aeromonas hydrophila, and is the "founding member" of a major family of PFTs found across many organisms.
One of the main advantages of aerolysin is that it forms very narrow pores that can tell apart molecules with much higher resolution than other toxins. Previous studies have shown that aerolysin can be used to "sense" several biomolecules, but there haven't been barely any studies on the relationship between aerolysin's structure and its molecular sensing abilities.
The researchers first used a structural model of aerolysin to study its structure with computer simulations. As a protein, aerolysin is made up of amino acids, and the model helped the scientists understand how those amino acids affect the function of aerolysin in general.
Once they had a grasp of that relationship, the researchers began to strategically change different amino acids in the computer model. The model then predicted the possible impact of each change on the overall function of aerolysin.
At the end of the computational process, the lead author produced sixteen genetically engineered, "mutant" aerolysin pores, embedded them in lipid bilayers to simulate their position in a cell membrane, and carried out various measurements (single-channel recording and molecular translocation experiments) to understand how ionic conductance, ion selectivity, and translocation properties of the aerolysin pore are regulated on a molecular level.
And with this approach, the researchers finally found what drives the relationship between the structure and the function of aerolysin: its cap. The aerolysin pore isn't just a tube that goes through the membrane, but also has a cap-like structure that attracts and tethers the target molecule and "pulls" it through the pore's channel. And the study found that the it is the electrostatics at this cap region that dictate this relationship.
"By understanding the details of how the structure of the aerolysin pore connects to its function, we can now engineer custom pores for various sensing applications," says the author. "These would open new, unexplored opportunities to sequence biomolecules as DNA, proteins and their post-translational modifications with promising applications in gene sequencing and biomarkers detection for diagnostics." The scientists have already filed a patent for their sequencing and characterization of the genetically engineered aerolysin pores.
https://actu.epfl.ch/news/turning-a-dangerous-toxin-into-a-biosensor/
https://www.nature.com/articles/s41467-019-12690-9
http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fsingle-molecule-sensing&filter=22
Structural determinants of bacterial toxin nanopore in single molecule sensing of peptides and nucleic acids
- 387 views
- Added
Edited
Latest News
High through-put technique to screen gene expression in multiple cells for drug discovery!
Predicting people's age by measuring proteins in blood
Changes in human brain exposed to extreme antarctic conditions
c-Jun overexpression to prevent CAR-T cells exhaustion
Molecular chaperones regulate alpha-synuclein in Parkinson's disease
Other Top Stories
Neuropeptide may be real cause of migraines
Immune gene prevents Parkinson's disease and dementia
Mechanism underlying itch sensation
Antioxidant role for lipid droplets in a stem cell niche
Mouse model of mitochondrial DNA mutations
Protocols
Dual-Angle Protocol for Doppler Optical Coherence Tomography to Improve Retinal Blood Flow Measur…
Detection of protein SUMOylation in vivo
In vivo analysis of protein sumoylation induced by a viral protein: Detection of HCMV pp71-induce…
Determination of SUMOylation sites
miR-Selection 3'UTR Target Selection Kit
Publications
Structural heterogeneity of α-synuclein fibrils amplified from patient brain extracts
Quantitative In Vivo Proteomics of Metformin Response in Liver Reveals AMPK-Dependent and -Indepe…
Quantitative In Vivo Proteomics of Metformin Response in Liver Reveals AMPK-Dependent and -Indepe…
Optimal solid state neurons
NAD+ augmentation restores mitophagy and limits accelerated aging in Werner syndrome
Presentations
Hypoxia Inducible Factor - 1 (HIF-1)
Intracellular Protein Degradation
Pathophysiology of Type 1 Diabetes
Plant Viruses
Regulation by changes in chromatin structure
Posters
AACC-2018-Infectious Disease
AACC-2018-Mass Spectrometry Applications
AACC-2018-Lipids/Lipoproteins
AACC-2018-Management
AACC-2018-Immunology-abstracts