title: Ultrasensitive detection of protein translocated through toxin pores in droplet-interface bilayers.
abstract: Many bacterial toxins form proteinaceous pores that facilitate the translocation of soluble effector proteins across cellular membranes. With anthrax toxin this process may be monitored in real time by electrophysiology, where fluctuations in ionic current through these pores inserted in model membranes are used to infer the translocation of individual protein molecules. However, detecting the minute quantities of translocated proteins has been a challenge. Here, we describe use of the droplet-interface bilayer system to follow the movement of proteins across a model membrane separating two submicroliter aqueous droplets. We report the capture and subsequent direct detection of as few as 100 protein molecules that have translocated through anthrax toxin pores. The droplet-interface bilayer system offers new avenues of approach to the study of protein translocation.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA, USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Fischer
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Holden
authors.forename: Brad L
authors.initials: BL
authors.lastname: Pentelute
authors.forename: R John
authors.initials: RJ
authors.lastname: Collier
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry* / Q000378:metabolism; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D004594:Electrophysiology / Q000379:methods*; D008051:Lipid Bilayers / Q000378:metabolism*; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry* / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002352:Carrier Proteins; D008051:Lipid Bilayers; D052899:Pore Forming Cytotoxic Proteins; C030325:anthrax toxin