Journal
ACS SENSORS
Volume 2, Issue 11, Pages 1619-1626Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acssensors.7b00481
Keywords
membrane protein; molecular filters; FhuA; beta-strands; nanopore; permeability
Funding
- China Scholarship Council (CSC) [201306350039]
- Innovative Medicines Initiatives [115525]
- European Union
- EFPIA
Ask authors/readers for more resources
Biological membranes are the perfect example of a molecular filter using membrane channels to control the permeability of small water-soluble molecules. To allow filtering of larger hydrophilic molecules we started from the known mutant channel FhuA Delta 1-160 in which the cork domain closing the channel had been removed. Here we further expand the pore diameter by copying the amino acid sequence of two beta-strands in a stepwise manner increasing the total number of beta-strands from 22 to 34. The pore size of the respective expanded channel protein was characterized by single-channel conductance. Insertion of additional beta-strands increased the pore conductance but also induced more ion current flickering on the millisecond scale. Further, polymer exclusion measurements were performed by analyzing single-channel conductance in the presence of differently sized polyethylene glycol of known polymer random coil radii. The conclusion from channel conductance of small channel penetrating polymers versus larger excluded ones suggested an increase in pore radii from 1.6 nm for FhuA Delta 1-160 up to a maximum of about 2.7 nm for +8 beta insertion. Integration of more beta-strand caused instability of the channel and exclusion of smaller sized polymer. FhuA Delta 1-160 + 10 beta and FhuA Delta 1-160 + 12 beta effective radius decreased to 1.4 and 1.3 nm, respectively, showing the limitations of this approach.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available