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Dynamics of bacteriophage ϕ29 DNA packaging: initiation and dependence on ionic conditions
Author(s) -
Rickgauer John Peter,
Fuller Derek N.,
Grimes Shelley,
Jardine Paul J.,
Anderson Dwight L.,
Smith Douglas E.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a954-d
Subject(s) - dna , bacteriophage , biophysics , optical tweezers , ionic bonding , capsid , chemistry , dynamics (music) , chemical physics , molecule , nanotechnology , crystallography , materials science , biology , biochemistry , physics , escherichia coli , optics , ion , gene , organic chemistry , acoustics
Optical tweezers measurements of the packaging of single DNA molecules into single bacteriophage ϕ29 proheads provide a method for understanding the detailed physical dynamics of an important step in the assembly of many viruses. Here we describe a novel method for studying the initiation of DNA packaging with optical tweezers. The success of this in situ initiation confirms an alternate pathway to the traditional DNA‐gp3 “lariat” model, and enables measurement of hitherto unreported early‐stage packaging dynamics. DNA translocation is shown to begin within a few seconds after dsDNA binds to the complex, and to exhibit the force‐velocity characteristics observed previously for motors stalled using a non‐hydrolyzable ATP analog. A sharp decrease in efficiency is observed if complexes are incubated in saturating ATP prior to exposure to DNA. Rates of DNA packaging spanning nearly the entire range of capsid filling are measured for native DNA‐gp3 and non‐native DNAs in varying ionic conditions.