@article{WOS:000661116600003,
 abstract = {``Pink″ or 1/f noise 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/f power spectral density. In the anthrax toxin channel
(PA(63)), it appears as fast voltage-independent current interruptions
between conducting and nonconducting states. This behavior hampers
potential development of PA(63) as an ion-channel biosensor. On the
bright side, the PA(63) flickering represents a mesmerizing phenomenon
to investigate. Notably, similar 1/f fluctuations 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 PA(63), 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/f noise in PA(63)
occurs as a result of ``hydrophobic gating″ at the phi-clamp region,
the phenomenon earlier observed in several water-filled channels
``fastened″ inside by the hydrophobic belts. The phi-clamp is a
narrow ``hydrophobic ring″ in the PA(63) lumen 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/f noise remains undetected in the F427A PA(63) mutant. This finding
can elucidate the functional purpose of 1/f noise and its possible role
in the transport of the enzymatic components of binary toxins.},
 author = {Yamini, Goli and Kanchi, Subbarao and Kalu, Nnanya and Abolfath, Sanaz
Momben and Leppla, Stephen H. and Ayappa, K. Ganapathy and Maiti, Prabal
K. and Nestorovich, Ekaterina M.},
 doi = {10.1021/acs.jpcb.0c10490},
 eissn = {1520-5207},
 issn = {1520-6106},
 journal = {JOURNAL OF PHYSICAL CHEMISTRY B},
 month = {JUN 3},
 number = {21},
 orcid-numbers = {Maiti, Prabal K/0000-0002-9956-1136
Kanchi, Subbarao/0000-0001-9147-0101},
 pages = {5466-5478},
 title = {Hydrophobic Gating and 1/f Noise of the Anthrax Toxin Channel},
 unique-id = {WOS:000661116600003},
 volume = {125},
 year = {2021}
}