Rjd. Reid et al., CHARACTERIZATION OF THE PROHEAD-PRNA INTERACTION OF BACTERIOPHAGE-PHI-29, The Journal of biological chemistry, 269(7), 1994, pp. 5157-5162
The small prohead RNA(pRNA) of the Bacillus subtilis bacteriophage phi
29 is essential for ATP dependent packaging of viral DNA. The 174-, 1
24-, and 120-residue forms of pRNA produced in vitro using T7 RNA poly
merase were equivalent in prohead binding and DNA packaging activity t
o pRNAs produced in phi 29-infected cells. pRNA binding to proheads, c
haracterized by the use of Northern hybridization and filter binding a
ssays, was specific, rapid, and irreversible in the presence of 10 mM
Mg2+. Proheads produced in phage-infected cells carried 5.8 +/- 2.7 co
pies of pRNA, and proheads assembled in Escherichia coil in the absenc
e of pRNA bound 6.0 +/- 3.5 copies of pRNA. Footprints of proheads on
pRNA generated with the ribonucleases A, T1, and V1 showed that nucleo
tides 22-84, 5' to 3', were protected from ribonuclease attack. Enhanc
ed cleavage at nucleotides 37-40 with ribonuclease V1 suggested a conf
ormational change of pRNA upon prohead binding.