title: Experimental test of connector rotation during DNA packaging into bacteriophage phi29 capsids.
abstract: The bacteriophage phi29 generates large forces to compact its double-stranded DNA genome into a protein capsid by means of a portal motor complex. Several mechanical models for the generation of these high forces by the motor complex predict coupling of DNA translocation to rotation of the head-tail connector dodecamer. Putative connector rotation is investigated here by combining the methods of single-molecule force spectroscopy with polarization-sensitive single-molecule fluorescence. In our experiment, we observe motor function in several packaging complexes in parallel using video microscopy of bead position in a magnetic trap. At the same time, we follow the orientation of single fluorophores attached to the portal motor connector. From our data, we can exclude connector rotation with greater than 99% probability and therefore answer a long-standing mechanistic question.
authors.affiliation: Department of Physics, Technical University, Munich, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Hugel
authors.forename: Jens
authors.initials: J
authors.lastname: Michaelis
authors.forename: Craig L
authors.initials: CL
authors.lastname: Hetherington
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Jardine
authors.forename: Shelley
authors.initials: S
authors.lastname: Grimes
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Walter
authors.forename: Wayne
authors.initials: W
authors.lastname: Falk
authors.forename: Dwight L
authors.initials: DL
authors.lastname: Anderson
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
mesh_terms: D017103:Bacillus Phages / Q000235:genetics*; D002213:Capsid / Q000737:chemistry*; D042003:DNA Packaging; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics*; D005453:Fluorescence; D009690:Nucleic Acid Conformation
chemical_list: D004279:DNA, Viral