The IDL of E. coli SSB links ssDNA and protein binding by mediating protein–protein interactions

Piero R. Bianco, Sasheen Pottinger, Hui Yin Tan, Trong Nguyenduc, Kervin Rex, Umesh Varshney

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The E. coli single strand DNA binding protein (SSB) is essential to viability where it functions in two seemingly disparate roles: it binds to single stranded DNA (ssDNA) and to target proteins that comprise the SSB interactome. The link between these roles resides in a previously under-appreciated region of the protein known as the intrinsically disordered linker (IDL). We present a model wherein the IDL is responsible for mediating protein–protein interactions critical to each role. When interactions occur between SSB tetramers, cooperative binding to ssDNA results. When binding occurs between SSB and an interactome partner, storage or loading of that protein onto the DNA takes place. The properties of the IDL that facilitate these interactions include the presence of repeats, a putative polyproline type II helix and, PXXP motifs that may facilitate direct binding to the OB-fold in a manner similar to that observed for SH3 domain binding of PXXP ligands in eukaryotic systems.

Original languageEnglish (US)
Pages (from-to)227-241
Number of pages15
JournalProtein Science
Issue number2
StatePublished - Feb 1 2017
Externally publishedYes


  • OB-fold
  • PXXP motif
  • RecG
  • RecO
  • SH3 domain
  • SSB

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology


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