title: Intersubunit coordination in a homomeric ring ATPase.
abstract: Homomeric ring ATPases perform many vital and varied tasks in the cell, ranging from chromosome segregation to protein degradation. Here we report the direct observation of the intersubunit coordination and step size of such a ring ATPase, the double-stranded-DNA packaging motor in the bacteriophage phi29. Using high-resolution optical tweezers, we find that packaging occurs in increments of 10 base pairs (bp). Statistical analysis of the preceding dwell times reveals that multiple ATPs bind during each dwell, and application of high force reveals that these 10-bp increments are composed of four 2.5-bp steps. These results indicate that the hydrolysis cycles of the individual subunits are highly coordinated by means of a mechanism novel for ring ATPases. Furthermore, a step size that is a non-integer number of base pairs demands new models for motor-DNA interactions.
authors.affiliation: Department of Physics and Jason L. Choy Laboratory of Single Molecule Biophysics, University of California, Berkeley, California 94720, USA.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Moffitt
authors.forename: Yann R
authors.initials: YR
authors.lastname: Chemla
authors.forename: K
authors.initials: K
authors.lastname: Aathavan
authors.forename: Shelley
authors.initials: S
authors.lastname: Grimes
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Jardine
authors.forename: Dwight L
authors.initials: DL
authors.lastname: Anderson
authors.forename: Carlos
authors.initials: C
authors.lastname: Bustamante
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D017103:Bacillus Phages / Q000201:enzymology*; D001412:Bacillus subtilis / Q000821:virology; D004279:DNA, Viral / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D019065:Virus Assembly
chemical_list: D004279:DNA, Viral; D021122:Protein Subunits; D000251:Adenosine Triphosphatases