1: J Biol Chem  1984 Jul 10;259(13):8338-44 

Internal motion of DNA in bacteriophages.

Ashikawa I, Furuno T, Kinosita K Jr, Ikegami A, Takahashi H, Akutsu H.

We have investigated internal motion of DNA in bacteriophages by measuring
fluorescence anisotropy decays of intercalated ethidium. The results showed
large suppression of the internal motion of the inner DNA; the interhelix
interaction of the DNA in the phage head is considered to enhance the effective
viscosity of the DNA rod and to restrict the angle of the internal motion.
Considering that the observed internal motion arises mainly from torsional
motion of the DNA, we have calculated the movable angles of the torsional motion
(the standard deviation of the torsional motion) of the DNA in the phage heads.
The magnitude of the calculated movable angles indicates the extent of
suppression of the DNA movement in the phage head; in lambda wild type phage,
the DNA is packed most rigidly in the head and the motion is found to be
restricted most severely. In a deletion mutant of lambda phage, whose inner DNA
content is deficient by 17.6%, steric hindrance from the interhelix DNA
interaction is decreased, and the DNA can move more easily. In T4 wild type
phage, although the extent of condensation of the inner DNA is the same as that
in lambda wild type phage, the DNA was fairly mobile. The presence of
glucosylated hydroxymethylcytosine is suggested to influence the rigidity of the
inner DNA or packaging mode of the DNA in the T4 head.

PMID: 6234311 [PubMed - indexed for MEDLINE]