J. Liu et al., THE ORDERED ASSEMBLY OF THE PHI-X174-TYPE PRIMOSOME .3. PRIB FACILITATES COMPLEX-FORMATION BETWEEN PRIA AND DNAT, The Journal of biological chemistry, 271(26), 1996, pp. 15656-15661
The properties of two mutant PriA proteins, PriA C439Y and PriA. C445Y
have been used to reveal the role of PriB during assembly of the phi
X174-type primosome, The replication defects of both mutant PriA prote
ins could be rescued by high concentrations of DnaT. Analysis of the f
ormation of intermediate complexes in primosome assembly and the effec
t of PriB on PriA binding to DNA demonstrated that the mutant PriA pro
teins could not form a PriA-PriB complex on DNA carrying a primosome a
ssembly site, Consequently, the mutant proteins also could not form Pr
iA-PriB-DnaT complexes at concentrations of DnaT sufficient to form su
ch a complex with wild-type PriA. In addition, PriB was found to stabi
lize wild-type but not mutant PriA proteins on DNA. At high concentrat
ions of DnaT, both mutant and wild-type PriA proteins could form a Pri
cA-DnaT complex and support PriB-independent phi X174 complementary st
rand DNA replication, Thus, during primosome assembly, PriB facilitate
s complex formation between PriA and DnaT.