Membrane-Embedded Channel of Bacteriophage Phi29 DNA-Packaging Motor for Translocation and Sensing of Double-Stranded DNA

Abstract

Living systems contain a wide variety of nanomachines and highly-ordered macromolecular structures with diverse functions. All linear double-stranded (ds) DNA viruses package their genome into a pre-formed protein shell via an Adenosine-5’-triphosphate (ATP) driven nanomotor. The novel and ingenious design of the bacteriophage phi29 DNA packaging motor with an elegant and elaborate channel has inspired its applications in nanotechnology. The central component of the phi29 motor is a connector composed of 12 copies of the protein gp10, which forms a dodecamer channel acting as a path for the translocation of dsDNA, which enters the protein shell during replication and exits into the host cell during infection. The diameter of the channel is 3.6 nm at the narrow end and 6 nm at its wider end. The connector has been successfully inserted into a lipid bilayer and exhibited robust capability for extremely reliable and precise assessment of the transportation of ions and DNA as revealed by single channel conductance assays. In addition, the bacteriophage phi29 DNA packaging motor exercised a one-way traffic property for dsDNA translocation from N-terminal entrance to C-terminal exit with a valve mechanism in DNA-packaging. These findings have important implications since artificial membrane architecture for DNA packaging motor would allow detailed investigations into discrete mechanisms of motor operation as well as future avenues for therapeutic dsDNA packaging, sampling, and delivery.