Force of ejection of DNA into host cell

Value 10 pN
Organism Bacteriophage Lambda
Reference Garcia HG, Grayson P, Han L, Inamdar M, Kondev J, Nelson PC, Phillips R, Widom J, Wiggins PA. Biological consequences of tightly bent DNA: the other life of a macromolecular celebrity. Biopolymers. 2007 Feb 5 85(2):115-30.PubMed ID17103419
Primary Source Grayson P, Evilevitch A, Inamdar MM, Purohit PK, Gelbart WM, Knobler CM, Phillips R. The effect of genome length on ejection forces in bacteriophage lambda. Virology. 2006 May 10 348(2):430-6PubMed ID16469346
Method osmotic pressure can be used to push on the DNA, freezing it in an equilibrium configuration where only a fraction of the DNA, from 0 to 100%, has been ejected. Though single particles are not observed with this technique, the osmotic suppression of ejection allows to effectively take a snapshot of a single moment in the ejection process. A series of such experiments was done on phage, demonstrating forces as high as 10 pN (the force corresponding to 25 atm of external osmotic pressure)
Comments pN=picoNewton=10^-12Newton. Since phi 29 and lambda are both packed to a similar DNA density, it is unclear whether the six fold difference in forces is caused by a difference (phi 29= 57pN, BNID 103129) between the phages or a difference in the experimental conditions.
Entered by Uri M
ID 103131