| Autor: |
Yamini, Goli, Kanchi, Subbarao, Kalu, Nnanya, Momben Abolfath, Sanaz, Leppla, Stephen H., Ayappa, K. Ganapathy, Maiti, Prabal K., Nestorovich, Ekaterina M. |
| Zdroj: |
The Journal of Physical Chemistry - Part B; June 2021, Vol. 125 Issue: 21 p5466-5478, 13p |
| Abstrakt: |
“Pink” or 1/fnoise is a natural phenomenon omnipresent in physics, economics, astrophysics, biology, and even music and languages. In electrophysiology, the stochastic activity of a number of biological ion channels and artificial nanopores could be characterized by current noise with a 1/fpower spectral density. In the anthrax toxin channel (PA63), it appears as fast voltage-independent current interruptions between conducting and nonconducting states. This behavior hampers potential development of PA63as an ion-channel biosensor. On the bright side, the PA63flickering represents a mesmerizing phenomenon to investigate. Notably, similar 1/ffluctuations are observed in the channel-forming components of clostridial binary C2 and iota toxins, which share functional and structural similarities with the anthrax toxin channel. Similar to PA63, they are evolved to translocate the enzymatic components of the toxins into the cytosol. Here, using high-resolution single-channel lipid bilayer experiments and all-atom molecular dynamic simulations, we suggest that the 1/fnoise in PA63occurs as a result of “hydrophobic gating” at the ϕ-clamp region, the phenomenon earlier observed in several water-filled channels “fastened” inside by the hydrophobic belts. The ϕ-clamp is a narrow “hydrophobic ring” in the PA63lumen formed by seven or eight phenylalanine residues at position 427, conserved in the C2 and iota toxin channels, which catalyzes protein translocation. Notably, the 1/fnoise remains undetected in the F427A PA63mutant. This finding can elucidate the functional purpose of 1/fnoise and its possible role in the transport of the enzymatic components of binary toxins. |
| Databáze: |
Supplemental Index |
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