Temperature Effect on Ionic Current and ssDNA Transport through Nanopores.
We have investigated the role of electrostatic interactions in the transport of nucleic acids and ions through nanopores. The passage of DNA through nanopores has so far been conjectured to involve a free-energy barrier for entry, followed by a downhill translocation where the driving voltage accelerates the polymer. We have tested the validity of this conjecture by using two toxins, α-hemolysin and aerolysin, which differ in their shape, size, and charge. The characteristic timescales in each toxin as a function of temperature show that the entry barrier is ∼15 kBT and the translocation barrier is ∼35 kBT, although the electrical force in the latter step is much stronger. Resolution of this fact, using a theoretical model, reveals that the attraction between DNA and the charges inside the barrel of the pore is the most dominant factor in determining the translocation speed and not merely the driving electrochemical potential gradient.
LAMBE, équipe MPI, CNRS-UMR 8587, Université d'Évry, Évry, France.
Linda
L
Payet
LAMBE, équipe MPI, CNRS-UMR 8587, Université d'Évry, Évry, France.
Marlène
M
Martinho
LAMBE, équipe MPI, CNRS-UMR 8587, Université d'Évry, Évry, France.
Céline
C
Merstorf
LAMBE, équipe MPI, CNRS-UMR 8587, Université de Cergy-Pontoise, Cergy-Pontoise, France.
Manuela
M
Pastoriza-Gallego
LAMBE, équipe MPI, CNRS-UMR 8587, Université d'Évry, Évry, France.
Juan
J
Pelta
Laboratoire Gulliver équipe NBP, CNRS-UMR 7083, ESPCI, Paris, France; CNRS UMI 3639, MechanoBiology Institute at National University of Singapore, Singapore, Singapore.
Virgile
V
Viasnoff
Laboratoire MSC, CNRS-UMR 7057, Université Denis Diderot, Paris, France.
Loïc
L
Auvray
Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts.
Murugappan
M
Muthukumar
LAMBE, équipe MPI, CNRS-UMR 8587, Université d'Évry, Évry, France. Electronic address: jerome.mathe@univ-evry.fr.
Jérôme
J
Mathé
D001427:Bacterial Toxins / Q000633:toxicity; D001692:Biological Transport / Q000187:drug effects; D004277:DNA, Single-Stranded; D006460:Hemolysin Proteins / Q000633:toxicity; D008567:Membranes, Artificial; D008962:Models, Theoretical; D009038:Motion; D058608:Nanopores; D010713:Phosphatidylcholines; D011108:Polymers; D052899:Pore Forming Cytotoxic Proteins / Q000633:toxicity; D055672:Static Electricity; D013696:Temperature
D001427:Bacterial Toxins; D004277:DNA, Single-Stranded; D006460:Hemolysin Proteins; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D011108:Polymers; D052899:Pore Forming Cytotoxic Proteins; C021091:staphylococcal alpha-toxin; C021016:1,2-diphytanoylphosphatidylcholine; C032676:aerolysin