4MZ9

Revised structure of E. coli SSB

Summary for 4MZ9

• Entry DOI: 10.2210/pdb4mz9/pdb
• Related: 1EYG 1QVC 1SRU
• Descriptor: Single-stranded DNA-binding protein (2 entities in total)
• Functional Keywords: single strand dna-binding domain, ssb, reco, exoi, recq, dnag, holc, dna binding protein
• Biological source: Escherichia coli
• Total number of polymer chains: 4
• Total formula weight: 75967.76

Authors

Oakley, A.J. (deposition date: 2013-09-29, release date: 2013-12-18, Last modification date: 2023-09-20)

Primary citation

Shishmarev, D.,Wang, Y.,Mason, C.E.,Su, X.C.,Oakley, A.J.,Graham, B.,Huber, T.,Dixon, N.E.,Otting, G.
Intramolecular binding mode of the C-terminus of Escherichia coli single-stranded DNA binding protein determined by nuclear magnetic resonance spectroscopy.
Nucleic Acids Res., 42:2750-2757, 2014

PubMed Abstract: Single-stranded DNA (ssDNA) binding protein (SSB) is an essential protein to protect ssDNA and recruit specific ssDNA-processing proteins. Escherichia coli SSB forms a tetramer at neutral pH, comprising a structurally well-defined ssDNA binding domain (OB-domain) and a disordered C-terminal domain (C-domain) of ∼ 64 amino acid residues. The C-terminal eight-residue segment of SSB (C-peptide) has been shown to interact with the OB-domain, but crystal structures failed to reveal any electron density of the C-peptide. Here we show that SSB forms a monomer at pH 3.4, which is suitable for studies by high-resolution nuclear magnetic resonance (NMR) spectroscopy. The OB-domain retains its 3D structure in the monomer, and the C-peptide is shown by nuclear Overhauser effects and lanthanide-induced pseudocontact shifts to bind to the OB-domain at a site that harbors ssDNA in the crystal structure of the SSB-ssDNA complex. (15)N relaxation data demonstrate high flexibility of the polypeptide segment linking the C-peptide to the OB-domain and somewhat increased flexibility of the C-peptide compared with the OB-domain, suggesting that the C-peptide either retains high mobility in the bound state or is in a fast equilibrium with an unbound state.

PubMed: 24288378
DOI: 10.1093/nar/gkt1238

Experimental method

X-RAY DIFFRACTION (2.2 Å)