title: Thermal unfolding of proteins probed at the single molecule level using nanopores.
abstract: The nanopore technique has great potential to discriminate conformations of proteins. It is a very interesting system to mimic and understand the process of translocation of biomacromolecules through a cellular membrane. In particular, the unfolding and folding of proteins before and after going through the nanopore are not well understood. We study the thermal unfolding of a protein, probed by two protein nanopores: aerolysin and α-hemolysin. At room temperature, the native folded protein does not enter into the pore. When we increase the temperature from 25 to 50 °C, the molecules unfold and the event frequency of current blockade increases. A similar sigmoid function fits the normalized event frequency evolution for both nanopores, thus the unfolding curve does not depend on the structure and the net charge of the nanopore. We performed also a circular dichroism bulk experiment. We obtain the same melting temperature (around 45 °C) using the bulk and single molecule techniques.
authors.affiliation: LAMBE, UMR 8587 CNRS-CEA-UEVE, Université d'Évry val d'Essonne, Évry, France.
authors.forename: Linda
authors.initials: L
authors.lastname: Payet
authors.forename: Marlène
authors.initials: M
authors.lastname: Martinho
authors.forename: Manuela
authors.initials: M
authors.lastname: Pastoriza-Gallego
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Betton
authors.forename: Loïc
authors.initials: L
authors.lastname: Auvray
authors.forename: Juan
authors.initials: J
authors.lastname: Pelta
authors.forename: Jérôme
authors.initials: J
authors.lastname: Mathé
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry*; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006460:Hemolysin Proteins / Q000737:chemistry*; D058608:Nanopores; D033902:Periplasmic Binding Proteins / Q000737:chemistry*; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry*; D058767:Protein Unfolding; D013696:Temperature
chemical_list: D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C461619:MalE protein, E coli; D033902:Periplasmic Binding Proteins; D052899:Pore Forming Cytotoxic Proteins; C032676:aerolysin