Chandramouli, Balasubramanian; Di Maio, Danilo; Mancini, Giordano; Brancato, Giuseppe
Introducing an artificial photo-switch into a biological pore: A model study of an engineered alpha-hemolysin

In recent years, engineered biological pores responsive to external stimuli have been fruitfully used for various biotechnological applications. Moreover, the strategy of tethering photo-switchable moieties into biomolecules has provided an unprecedented temporal control of purposely designed nanodevices, as demonstrated, for example, by the light-mediated regulation of the activity of enzymes and biochannels. Inspired by these advancements, we propose here a de novo designed nanodevice featuring the alpha-hemolysin (alpha HL) membrane channel purposely functionalized by an artificial "on/off' molecular switch. The switch, which is based on the photoisomerization of the azobenzene moiety, introduces a smart nano-valve into the natural non-gated pore to confer tunable transport properties. We validated through molecular dynamics simulations and free energy calculations the effective inter-conversion of the engineered alpha HL pore between two configurations corresponding to an "open" and a "closed" form. The reported switchable translocation of a single-stranded DNA fragment under applied voltage supports the promising capabilities of this nanopore prototype in view of molecular sensing, detection and delivery applications at single-molecule level. (C) 2016 Elsevier B.V. All rights reserved.


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