The primosome attaches 1-10 RNA nucleotides to the single stranded DNA creating a DNA-RNA hybrid.
Assembly of the Escherichia coli primosome requires six proteins, PriA, PriB, PriC, DnaB, DnaC, and DnaT, acting at a primosome assembly site (pas) on an SSBcoated single-stranded (8s) DNA.
PriC, DnaB, DnaC, and DnaT then act on the PriAPriB- DNA complex to yield the primosome.
In Bacillus subtilis, genetic analysis has revealed three primosomal proteins, DnaB, DnaD, and DnaI, that have no obvious homologues in E. coli.
Our biochemical analysis of the DnaB and DnaD proteins unravels their role in primosome assembly.