NMR structure of a stable "OB-fold" sub-domain isolated from staphylococcal nuclease.Alexandrescu, A.T., Gittis, A.G., Abeygunawardana, C., Shortle, D.
(1995) J Mol Biol 250: 134-143
- PubMed: 7608966
- DOI: https://doi.org/10.1006/jmbi.1995.0365
- Primary Citation of Related Structures:
- PubMed Abstract:
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.
Department of Biological Chemistry, Johns Hopkins Medical Institutions, Baltimore, MD 21205, USA.