Due to scheduled maintenance work, this service may not be available on Monday January 22nd between 08.00 am and 9.00 am CEST.
To improve security and privacy, we are moving our web pages and services from HTTP to HTTPS.
To give users of web services time to transition to HTTPS, we will support separate HTTP and HTTPS services until the end of 2017.
From January 2018 most HTTP traffic will be automatically redirected to HTTPS. [more...]
View this page in https
PROSITE documentation PDOC00602 [for PROSITE entry PS50935]

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

PROSITE is copyright. It is produced by the SIB Swiss Institute Bioinformatics. There are no restrictions on its use by non-profit institutions as long as its content is in no way modified. Usage by and for commercial entities requires a license agreement. For information about the licensing scheme send an email to
Prosite License or see: prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)