InterPro domain: IPR000424

The Escherichia coli single-strand binding protein [ 1 ] (gene ssb), also known as the helix-destabilising protein, is a protein of 177 amino acids. It binds tightly, as a homotetramer, to single-stranded DNA (ss-DNA) and plays an important role in DNA replication, recombination and repair. Closely related variants of SSB are encoded in the genome of a variety of large self-transmissible plasmids. SSB has also been characterized in bacteria such as Proteus mirabilis or Serratia marcescens. Eukaryotic mitochondrial proteins that bind ss-DNA and are probably involved in mitochondrial DNA replication are structurally and evolutionary related to prokaryotic SSB.

Primosomal replication protein N (PriB) is a specialist protein from bacteria that binds single-stranded DNA at the primosome assembly site (PAS). The primosome is a mobile multiprotein replication priming complex which is believe to operate on the lagging-strand template at the E. coli DNA replication fork [ 2 ]. The primosome consists of one monomer of PriC and DnaT, two monomers of PriA, two dimers of PriB and one hexamer of DnaB [ 3 ].

1. The single-stranded DNA-binding protein of Escherichia coli. Microbiol. Rev. 54, 342-80
2. The priB and priC replication proteins of Escherichia coli. Genes, DNA sequence, overexpression, and purification. J. Biol. Chem. 266, 13988-95
3. The ordered assembly of the phiX174-type primosome. III. PriB facilitates complex formation between PriA and DnaT. J. Biol. Chem. 271, 15656-61