DNA packaging and ejection forces in bacteriophage

Submitted by Ajaykumar Gopal on Sun, 07/06/2008 - 21:41.

Publication Type:

Journal Article

Authors:

Kindt, J.; Tzlil, S.; Ben-Shaul, A.; Gelbart, W.

Source:

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Volume 98, Number 24, p.13671-13674 (2001)

URL:

http://www.pnas.org/content/98/24/13671.full.pdf

Keywords:

DOUBLE-STRANDED DNA; ESCHERICHIA-COLI; HEADS; CONFORMATION; ORGANIZATION; STRESS; LAMBDA; MODEL

Abstract:

We calculate the forces required to package (or, equivalently, acting to eject) DNA into (from) a bacteriophage capsid, as a function of the loaded (ejected) length, under conditions for which the DNA is either self-repelling or self-attracting. Through computer simulation and analytical theory, we find the loading force to increase more than 10-fold (to tens of piconewtons) during the final third of the loading process, correspondingly, the internal pressure drops 10-fold to a few atmospheres (matching the osmotic pressure in the cell) upon ejection of just a small fraction of the phage genome. We also determine an evolution of the arrangement of packaged DNA from toroidal to spool-like structures.