On the electron transfer through Geobacter sulfurreducens PilA protein

Geobacter sulfurreducens pili composed of the Type IV pili structural peptide PilA have been implicated as efficient electronic conductors. Though investigated experimentally, no detailed theoretical studies have been performed to date that provide quantitative estimation of the transmission spectru...

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Published inJournal of polymer science. Part B, Polymer physics Vol. 53; no. 24; pp. 1706 - 1717
Main Authors Lebedev, Nikolai, Mahmud, Syed, Griva, Igor, Blom, Anders, Tender, Leonard M
Format Journal Article
LanguageEnglish
Published Hoboken Wiley 15.12.2015
Wiley Subscription Services, Inc
Subjects
amino acids
Coherence
conductive pili
electric power
electroactive biofilm
Electrodes
Electron transfer
Electron tunneling
Electronics
electrons
fimbriae
Fragments
Geobacter sulfurreducens
molecular electronics
nuclear magnetic resonance spectroscopy
Peptides
polymers
protein conductance
Proteins
traps
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Summary:Geobacter sulfurreducens pili composed of the Type IV pili structural peptide PilA have been implicated as efficient electronic conductors. Though investigated experimentally, no detailed theoretical studies have been performed to date that provide quantitative estimation of the transmission spectrum, electron transfer (ET) paths, efficiency of current generation, and other factors needed for understanding possible mechanisms of conductivity. In the present work, we calculate from first principles the possibilities of electron tunneling through 3 PilA fragments which structure was identified recently by NMR. The results indicate that positively charged amino acids, arginines and lysines form electrostatic traps in the middle of the peptide preventing ET at low bias voltages (<∼6 V). At higher biases the traps are filled with electrons making possible sequential electron tunneling through the central part of the protein. In addition, leucines and phenylalanines form ET loops facilitating electron stabilization within the protein and sequential ET. Our results indicate that ET through the PilA protein cannot occur by coherent ET, but suggest a sequential (incoherent) mechanism. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1706–1717
Bibliography:http://dx.doi.org/10.1002/polb.23809
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ISSN:0887-6266
1099-0488
DOI:10.1002/polb.23809