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
- 3,283 views
- Added
Edited
Latest News
New origin of deep brain waves
By newseditor
Posted 17 Apr
Starving cells hijack prote…
By newseditor
Posted 17 Apr
Miniature battery-free epid…
By newseditor
Posted 17 Apr
Molecular causes of differe…
By newseditor
Posted 16 Apr
Cell's 'garbage disposal' h…
By newseditor
Posted 16 Apr
Other Top Stories
Neonatal hypoxia affects learning and neuronal firing!
Read more
What doesn't kill you makes you stronger!
Read more
Could vitamin B3 treat acute kidney injury?
Read more
MicroRNA (miRNA) misregulation in Huntington's disease
Read more
'Hearing' protein identified!
Read more
Protocols
MemPrep, a new technology f…
By newseditor
Posted 08 Apr
A tangible method to assess…
By newseditor
Posted 08 Apr
Stem cell-derived vessels-o…
By newseditor
Posted 06 Apr
Single-cell biclustering fo…
By newseditor
Posted 01 Apr
Modular dual-color BiAD sen…
By newseditor
Posted 31 Mar
Publications
The immunobiology of herpes…
By newseditor
Posted 17 Apr
Circulating microbiome DNA…
By newseditor
Posted 17 Apr
Spindle oscillations in com…
By newseditor
Posted 17 Apr
Oligodendroglial macroautop…
By newseditor
Posted 17 Apr
COPII with ALG2 and ESCRTs…
By newseditor
Posted 17 Apr
Presentations
Hydrogels in Drug Delivery
By newseditor
Posted 12 Apr
Lipids
By newseditor
Posted 31 Dec
Cell biology of carbohydrat…
By newseditor
Posted 29 Nov
RNA interference (RNAi)
By newseditor
Posted 23 Oct
RNA structure and functions
By newseditor
Posted 19 Oct
Posters
A chemical biology/modular…
By newseditor
Posted 22 Aug
Single-molecule covalent ma…
By newseditor
Posted 04 Jul
ASCO-2020-HEALTH SERVICES R…
By newseditor
Posted 23 Mar
ASCO-2020-HEAD AND NECK CANCER
By newseditor
Posted 23 Mar
ASCO-2020-GENITOURINARY CAN…
By newseditor
Posted 23 Mar