NMR Structure of a Stable "OB-fold" Sub-domain Isolated from Staphylococcal Nuclease

Andrei T. Alexandrescu, Apostolos G. Gittis, Chitrananda Abeygunawardana, David Shortle

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44 Scopus citations


Similar folds often occur in proteins with dissimilar sequences. The OB-fold forms a part of the structures of at least seven non-homologous proteins that share either oligonucleotide or oligosaccharide binding functions. A 1-103 fragment corresponding to the OB-fold of the 149 amino acid residue staphylococcal nuclease gives NMR spectra characteristic of an unfolded protein, i.e. the wild-type nuclease sequence is insufficient to maintain a stable tertiary structure in the absence of the C-terminal one-third of this single-domain protein. By contrast, the 1-103 fragment of nuclease with the mutations Val66Leu and Gly88Val adopts a stable tertiary structure. The NMR solution structure of this latter fragment is a close variation of the OB-fold found in the X-ray structure of the parent protein. The Val66Leu and Gly88Val mutations appear to stabilize tertiary structure by consolidating the hydrophobic core of the nuclease OB-fold sub-domain. Taken together, these results suggest that recurrent structural motifs such as the OB-fold may in some cases represent vestiges of autonomous folding units that, during evolution, have become integrated into more complex cooperative folding domains.

Original languageEnglish (US)
Pages (from-to)134-143
Number of pages10
JournalJournal of molecular biology
Issue number2
StatePublished - Jul 7 1995


  • NMR
  • OB-fold
  • evolution
  • protein folding
  • protein structure

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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