PROSITE documentation PDOC00602
Single-strand binding (SSB) domain profile


The Escherichia coli single-strand binding protein [1] (gene ssb), also known as the helix-destabilizing 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. Proteins currently known to belong to this subfamily are listed below [2]:

  • Mammalian protein Mt-SSB (P16).
  • Xenopus Mt-SSBs and Mt-SSBr.
  • Drosophila MtSSB.
  • Yeast protein RIM1.

The SSB domain is a module of about 100 amino acids that is found in the N-terminal part of bacterial SSB proteins. It possesses conserved residues that are responsible for binding to ssDNA, tetramerization and stabilization of the monomer fold [3].

The profile we developed covers the entire SSB domain.

Last update:

October 2003 / Patterns removed, profile added and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

SSB, PS50935; Single-strand binding (SSB) domain profile  (MATRIX)


1AuthorsMeyer R.R. Laine P.S.
TitleThe single-stranded DNA-binding protein of Escherichia coli.
SourceMicrobiol. Rev. 54:342-380(1990).
PubMed ID2087220

2AuthorsStroumbakis N.D. Li Z. Tolias P.P.
TitleRNA- and single-stranded DNA-binding (SSB) proteins expressed during Drosophila melanogaster oogenesis: a homolog of bacterial and eukaryotic mitochondrial SSBs.
SourceGene 143:171-177(1994).
PubMed ID8206370

3AuthorsDabrowski S. Olszewski M. Piatek R. Brillowska-Dabrowska A. Konopa G. Kur J.
TitleIdentification and characterization of single-stranded-DNA-binding proteins from Thermus thermophilus and Thermus aquaticus - new arrangement of binding domains.
SourceMicrobiology 148:3307-3315(2002).
PubMed ID12368464

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